Infectious Diseases

Question 1

A 42-year-old man presents to your clinic with history of a slowly-enlarging painless scrotal mass over the past months. He has previous history of unilateral cryptorchidism which required orchiopexy. On examination, a solid scrotal lump is palpated. Which one of the following would be the next best step in management?

A. Measuring serum alpha fetoprotein.
B. Measuring serum human beta chorionic gonadotropin (βHCG).
C. CT scan of the abdomen and pelvis.
D. Ultrasonography of the scrotum.
E. Scrotal needle biopsy.

Answer 1

D. Ultrasonography of the scrotum.

All solid scrotal lumps should be considered malignant until proven otherwise. In approach to scrotal masses the most appropriate next step is to request an ultrasound to further evaluate the scrotal mass.

Ultrasound of the testes can reliably diagnose the testicular tumor with considerable precision and can also detect any invasion of the tunica albuginea.

This man also has undergone orchipexy that is a risk factor for development of testicular cancer.

Risk factors of development of testicular cancer include personal or family history of any of the following:
* Cryptorchidism (undescended testes)
* Orchiopexy
* Testicular atrophy
* Previous testicular cancer

Option A and B: Tumor markers (alpha fetoprotein and beta HCG) are not requested unless ultrasound suggests cancer.

Option C: CT scan of the abdomen, pelvis and chest is done for staging purposes and only considered after confirmed diagnosis of testicular malignancy.

Option E: Needle scrotal biopsy should be avoided because of potential risk of tumor implanting malignant cells in the scrotal wall.

Question 2

A 20-year-old man presents to the Emergency Department with acutely painful scrotal swelling for the past 12 hours. Evaluation establishes the diagnosis of epidiymoorchitis. Which one of the following is the most likely causative organism?

A. E.coli.
B. Staphylococcus aureus.
C. Chlamydia.
D. Neisseria gonorrhea.
E. Treponema pallidum.

Answer 2

C. Chlamydia

Causative organism in epididymo-orchitis varies based on the age of the patient:

Children and men older than 35 years:
Urinary coliforms (e.g., E coli, Pseudomonas species, Proteus species, Klebsiella species) are the most common causes. Less frequently, pathogens such as Ureaplasma urealyticum, Corynebacterium species, Mycoplasma species, and Mima polymorpha have also been isolated. Systemic Hemophilus influenzae and Neisseria meningitides infections are rare yet possible causes.

Sexually active men younger than 35 years:
Chlamydia is the most common cause in sexually active men younger than 35 years (accounting for up to 50% of cases, although laboratory evidence of Chlamydia may be absent in up to 90% of cases). Infections with Neisseria gonorrhea, Treponema pallidum, Trichomonas species, and Gardnerella vaginalis also occur in this population.
In this sexually active man, who is younger than 35 years.
* RACGP - AFP - Acute scrotal pain
* Medscape - Epididymitis

Question 3

A 25-year-old Asian woman with no known tuberculosis contact has a positive Tuberculin skin test (TST) in a workup for immigration. A chest X-ray is performed and is completely normal. She has no cough, fever or sputum. Physical examination is unremarkable. Which one of the following is the next best step in management?

A. BCG vaccination.
B. Isoniazid for 9months.
C. Repeat the chest X-ray in 6months.
D. Repeat the TST in 2 weeks.
E. Isoniazid for 2 months.

Answer 3

B. Isoniazid 9 months

Every person with a positive tuberculin skin test (TST), also known as Mantoux test, or interferon gamma release assay (IGRA), should undergo a full investigation for active TB infection, including chest X-ray and sputum smear for acid-fast bacilli (AFB) and culture. If the diagnosis of active disease is established, the patient should receive full four-drug therapy with isoniazid, ethambutole, pyrizinamide, and rifampicin.

LTBI denotes infection with mycobacterium tuberculosis without any active disease. This is why monotherapy with isoniazid for 6 to 9 months is required for such patients.

A positive chest X-ray indicates either healed TB with residual traction scars or active TB infection. For this reason, if an abnormal chest X-ray is the only finding in addition to a positive TST or IGRA, three sputum samples should be obtained for acid fast bacilli (AFB) stain and culture.

If all three samples are negative, active TB infection is excluded, and the patient should be treated for LTBI. With even one positive sample in the presence of chest X-ray abnormalities, active TB infection is the definite diagnosis. Any positive result needs to be discussed with a clinician experienced in TB management before starting any treatment.

Treatment of LTBI requires at least 6 months of isoniazid.

• RACGP - Tuberculosis testing
• Australian Prescriber - Testing for tuberculosis
• Therapeutic Guidelines – Antibiotics: available on: http://tg.org.au

Question 4

Which one of the following is not a feature of mycoplasma pneumonia?

A. Headache.
B. High fever.
C. Pleuretic chest pain.
D. Cough.
E. Myalgia.

Answer 4

B. High fever

The prodromal phase is characterized by headache, malaise, myalgia and mild fever. Fever more than 39°C is rare in mycoplasma infection and should raise suspicion against another cause.

Cough in mycoplasma is usually incessant and often non-productive (dry) to mildly productive.

Sputum discoloration may be seen late in the course of the disease.

http://emedicine.medscape.com/article/1941994-clin

Question 5

A 27-year-old man is seen in the emergency department with complaints of dry cough, fever, dyspnea, and diarrhea, which began 4 days after an upper respiratory tract infection. On physical examination, he has a respiratory rate of 22 breaths per minute and temperature of 41°C. On auscultation, bilateral basal crackles are noted. Chest X-ray is remarkable for bilateral interstitial infiltrates. Which one of the following is the most appropriate initial therapy for this patient?

A. Amoxicillin/clavulanate.
B. Penicillin.
C. Azithromycin.
D. Ciprofloxacin.
E. Trimethoprim-sulfamethoxazole.

Answer 5

C. Azithromycin

This man has the characteristic features of an atypical pneumonia. The most common causative organism in atypical pneumoniae is mycoplasma pneumoniae, but in infections with this organism the fever is unlikely to exceed 39°C.

Signs and symptoms of atypical pneumonia in addition to high fever and gastrointestinal problems make infection with legionella pneumophila pneumonia (legionnaires’ disease) the most likely diagnosis. Macrolides (e.g. azithromycin) are antibiotics of choice for all atypical pneumonias, including legionnaires disease. They also may cover streptococcus pneumonia.

http://emedicine.medscape.com/article/220163-clini * http://emedicine.medscape.com/article/220163-overv

Question 6

A 24-year-old pregnant woman, who is 19 weeks pregnant, presents to your office complaining of frequency, urgency and dysuria. Further investigations establish the diagnosis of urinary tract infection. The culture results are still pending. The patient has history of allergic reaction to penicillin manifesting as a rash. Which one of the following would be the antibiotic of choice for treating this patient?

A. Amoxicillin.
B. Clarithromycin.
C. Aminoglycosides.
D. Tetracyclines.
E. Cephalexin.

Answer 6

E. Cephalaxin

The antibiotic of choice for empirical treatment of urinary tract infection (UTI) in pregnancy is cephalexin. Nitrofurantoin and amoxicillin-clavulanate are second- and third-line medications, respectively. Patients allergic to penicillin manifested as a rash can be still rather safely treated with cephalexin. If the presentation of allergy to penicillin was anaphylaxis, cephalosporins were not recommended, and the patient should be treated with nitrofurantoin.

Asymptomatic bacteriuria (>105 colony count in urine culture of an asymptomatic woman) in pregnancy should also be treated with a one week course of antibiotics. Urine culture should be repeated 48 hours after completion of treatment to confirm resolution of the infection.

Macrolides e.g. clarithromycin are *not recommended *for treatment of UTI.

Aminoglycosides are category D and should not be used during pregnancy, unless there is severe gram negative sepsis.

Tetracyclins are contraindicated in pregnancy due to their potential teratogenic effects.

Question 7

A 6-year-old boy is brought to your practice with fever and cough for 7 days. On examination, he has a blood pressure of 100/70 mmHg, pulse rate of 110 bpm, respiratory rate of 22 breaths per minute and a temperature of 37.7°C. There is no respiratory distress. Lung auscultation reveals bilateral crackles at lung bases. Chest X-ray is performed that is remarkable for bilateral patchy infiltrates more prominent in the left upper lobe.

Blood test is :
HB 130g/L (120-150)
WCC 14x109/L (4-11)
Neutrophils 6.5x 109/L (2.0-7.5)
Lymphocytes 3.7x109/L (1.5-4.0)
Platelets 180x109/L (150-400)

Which one of the following is the most likely diagnosis?

A. Streptococcus viridians.
B. Mycoplasma pneumoniae.
C. Adenovirus.
D. Respiratory syncytial virus.
E. Hemophilus influenza.

Answer 7

B. Mycoplasma pneumoniae

The clinical findings and radiological findings of diffuse patchy infiltrates are highly suggestive of atypical pneumonia.

Viral pneumonia is the most common cause of atypical pneumonia in children younger than 2 years.

Mycoplasma pneumoniae is the most common causative organism in this age group (school-aged children).

Patients with mycoplasma pneumoniae usually experiences a prodromal phase characterized by headache, malaise, myalgia and mild fever. Fever more than 39°C is rare in mycoplasma infection and should always raise suspicion against another cause.

Usually the patient is not very ill
Mycoplasma pneumonia has a more prolonged course, compared to viral pneumonia.
Like other pulmonary diseases, chest X-ray is the best initial diagnostic test.

*http://emedicine.medscape.com/article/1941994-over
* Therapeutic Guidelines - Respiratory; available on: http://tg.org.au * AMC Handbook of Multiple Choice Questions – page 543

Question 8

A 57-year-old man presents to your GP practice with progressive cough, fever and malaise for the past 3 months. His background history includes smoking for 20 years and working in pottery industry for 30 years. Five years ago, he developed shortness of breath, for which he sought medical care and was diagnosed with silicosis. Which one of the following can be the cause for his recent condition?

A. Bronchogenic carcinoma.
B. Tuberculosis.
C. Chronic obstructive pulmonary disease.
D. Mesothelioma.
E. Pneumonia.

Answer 8

B. Tuberculosis

People who have chronic exposure to silica (miners, quarry workers, potters, etc.) may develop silicosis, which is an occupational interstitial lung disease. Pulmonary silicosis presents with exertional dyspnea due to progressive fibrosis of the lung parenchyma. Typical radiologic findings vary based on the severity and course of the disease and may include small nodular opacities (< 1 cm) in the upper lung zones and reticular changes and honey-combing (a late finding).

Although bronchogenic carcinoma is another possibility in heavy smokers with exposure to silica, it is not usually associated with fever and malaise. With fever and malaise and the history of silicosis, TB is more likely than bronchogenic carcinoma.

Smoking history makes chronic obstructive pulmonary disease (COPD) another possibility, but it does not cause fever and malaise unless an infection superimposes the condition. It is unlikely for a COPD patient to have lung infection as the first presentation of the disease.

Mesothelioma is a very rare malignancy of the pleura and is associated with asbestosis. It presents with pleuretic chest pain, pleural effusion and pleural thickening and calcification on imaging.

With symptoms persisting for three months, pneumonia is unlikely.

Question 9

Which one of the following conditions is likely to cause the oral lesions shown in the accompanying photograph in a 67-year-old man?

A. HIV.
B. Use of systemic corticosteroids.
C. Diabetes mellitus.
D. Chronic xerostomia.
E. All of the above.

Answer 9

E. All of the above

The photograph shows the oral Candidiasis (thrush) it colonizes the oral cavity in 60-75% of population, but the infection often occurs in those with immunodeficiency. These patches are easily scraped off, leaving only an underlying red patch.

Risk factors to development of oral Candidiasis include :
* Immunodeficiency
* Cytotoxic therapy
* Broad spectrum antibiotics
* Corticosteroids including inhaled corticosteroids
* Diabetes mellitus
* HIV
* Debility
* Anemia (iron, folic acid, or B12 deficiency)
* Dentures
* Chronic xerostomia

Question 10

A 69-year-old woman presents to your clinic with complaint of vaginal discharge. As a part of workup you perform a urine PCR test for gonorrhea and Chlamydia. The result is positive for gonorrhea. You tell her about the results and that gonorrhea is a sexually transmissible disease. She mentions that she has not had any sexual relationship with anyone whatsoever. Which one of the following will be the next best step in management?

A. Repeat the PCR test.
B. Give a single dose of ceftriaxone.
C. Give a single dose of azithromycin.
D. Arrange for hysteroscopy.
E. Counsel her about treatment.

Answer 10

E. Counsel her about treatment

Currently, a nucleic acid amplification test (NAAT) such as PCR is recommended as the optimal method for the diagnosis of genital tract infections caused by Neisseria gonorrhea and Chlamydia trachomatis in men and women with or without symptoms. Samples for NAATs can be collected from vagina or endocervix, urine (male and female) or urethra (only men).
Compared with culture, commercially available NAATs offer rapid results (within hours) and are generally more sensitive than culture. Cultures are only recommended when drug resistance is suspected.

In situations where positive test results are not supported by sexual history or clinical findings (such as in this scenario), retesting the patient with a different NAAT or culture is recommended. A decision to delay treatment until retesting confirms the diagnosis should be made in consultation with the patient. Patients should be counselled about prompt treatment after a positive screening test because an additional test might be falsely negative. Since the treatment of Chlamydia trachomatis and Neisseria gonorrhea is safe and relatively inexpensive, the patient might choose to be treated empirically without further testing or wait for the repeated test result.

Question 11

A 31-year-old woman presents with painful genital wart over the labia majora and minora. She is 38-week pregnant. Which one of the following is the next best step in management?

A. Take a piece of wart for PCR.
B. Obtain blood for culture.
C. Observer until after delivery.
D. Cryotherapy.
E. Excision of the lesion.

Answer 11

D. Cryotherapy

Higher human papilloma virus (HPV) infection rates have been reported in pregnant women. If condyloma develops, rapid growth can be observed. Contributing factors include immune system suppression during pregnancy and hormonal changes.
Small asymptomatic lesions do not require treatment as most of them resolve after delivery. Large lesions can be treated with cryotherapy or keratolytics such as trichloracetic acid (TCA) or bichloracetic acid (BCA) as the preferred methods during pregnancy. Recurrences should be treated with same methods if complete response had occurred.
Interferon, podophyllin, podophyllotoxin, imiquimod and 5-fluorouracil are topical agents that chemically ablate warts. Except imiquimod, these agents are contraindicated throughout pregnancy. Although imiquimod is category B1, there is not enough evidence regarding the safety of imiquimod during pregnancy, and it can be used after the pregnant woman is fully informed.

Question 12

A 56-year-old Victorian farmer presents to your GP clinic with chest tightness and coughing for the past 2 months. He also mentions vague right upper quadrant abdominal pain. On examination, no remarkable findings are noted except for mildly jaundiced sclera. Which one of the following could be the most likely diagnosis?

A. Hydatid cyst.
B. Q fever.
C. Ross River fever.
D. Brucellosis.
E. Dengue fever.

Answer 12

A. Hydatid cyst

The clinical picture, suggestive of lung and hepatic involvement, and the occupation of the patient make echinococcus infection (hydatid cyst) the most likely diagnosis.
In Australia, most hydatid infections are passed between sheep ad dogs, although other animals including horses, kangaroos, dingoes and foxes may be involved.

People become infected by ingesting eggs of the parasite, usually while there is a hand-to-mouth transfer of eggs in dog feces. This can occur when handling dogs or objects (including food and water) soiled with dog feces. Person-to-person or sheep-to-person transmission does not occur.
The pressure effect of the cyst on the liver can produce symptoms of obstructive jaundice and abdominal pain. With biliary rupture, the classic triad of biliary colic, jaundice and urticaria is observed. Passage of hydatid membranes in vomit (hydatid emesia) and passage of membrane in the stool (hydatid enterica) may rarely occur.

Involvement of the lungs produces chronic cough, dyspnea, pleuretic chest pain and hemoptysis. Expectoration of cyst membrane and fluid is observed with intrabronchial rupture.

Question 13

A 65-year-old man presents to your clinic with a painful swelling below his left eye. The lesion is illustrated in the accompanying photograph. Which one of the following would be the most appropriate next step in management?

A. Incision and drainage.
B. Cold compression.
C. Warm compression.
D. Antibiotics.
E. Topical steroids.

Answer 13

D. Antibiotics

Dacryocystitis is an infection of the lacrimal sac often due to nasolacrimal duct obstruction. It presents as a swollen, red, pus-filled sac below the medial aspect of the eye.

• Swelling and redness over the medial canthus
• Possible abscess formation in severe cases
• History of a watery eye

1. Hot Compresses: Apply to the affected area to reduce inflammation.
2. Massaging: Gently massage the tear sac and nasolacrimal duct.
3. Astringent Eye Drops: Use zinc sulfate 0.25% + phenylephrine 0.12%, 1 or 2 drops three times daily.
4. Topical Antibiotics: Use chloramphenicol if there is conjunctivitis.

1. Systemic Antibiotics: Start oral antibiotics to prevent the spread of infection. The choice of antibiotics is guided by Gram-stain and culture results.
   
   • Empiric choices: di/flucloxacillin or amoxicillin-clavulanate.
2. Intravenous Antibiotics: Indicated if there is:
   
   • Orbital cellulitis
   • Significant periorbital/facial cellulitis
   • Marked systemic symptoms (e.g., fever)

1. Surgical Intervention: Perform a dacryocystorhinostomy after the infection has subsided with adequate antibiotic therapy.

1. Mild Cases: Manage with hot compresses, massaging, astringent eye drops, and topical antibiotics if needed.
2. Severe Cases: Start systemic antibiotics immediately, followed by intravenous antibiotics if complications arise.
3. Post-Infection: Perform surgical intervention (dacryocystorhinostomy) once the infection is controlled.

The picture shows a swollen, red, puss-filled sac below the medial aspect of the left eye suggestive of dacryocystitis. Dacryocystitis is infection of the lacrimal sac often secondary to obstruction of the nasolacrimal duct. It presents with inflammation localized over the medial canthus. The condition may vary in clinical presentation from mild (such as in infants) to more severe forms with abscess formation such as in this case. There is often a history of watery eye for months beforehand.
Mild cases are managed with hot compresses and massaging the tear sac and nasolacrimal duct (the mainstay of the management) and astringent eye drops (e.g. zinc sulfate 0.25% + phenylephrine 0.12%, 1 or 2 drops 3 times daily). Topical antibiotics such as chloramphenicol are used if there is concomitant conjunctivitis.
More severe cases of dacryocystitis are often caused by Staphylococcus aureus or Streptococcus pyogenes, but occasionally Gram-negative and anaerobes can be the culprits. Systemic antibiotic therapy is always required as the most important initial step to limit the likelihood of infection spreading to adjacent areas such as the orbit, and serious complications such as orbital cellulitis. Although, the most appropriate choice of antibiotics are guided by Gram-stain and culture, di/flucloxacillin or amoxicillin-clavulanate, orally, should be started while the results are pending.
Intravenous route is used if there is orbital celllulitis, significant periorbital/ facial cellulitis, or if the patient has marked systemic symptoms (e.g. fever).
Antibiotic therapy is then followed by surgical treatment after the infection has subsided with adequate antibiotic therapy. For dacryocystitis, an dacryocystorhinostomy is preferred after several days of initiating antibiotic therapy.

Question 14

Six days ago, a 30-year-old man presented to your practice with complaints of acute sore throat and a fever of 39.2°C. On examination, he had red swollen tonsils with exudate. He was prescribed amoxicillin. Today, he has presented with a non- blanching pruritic rash. Which one of the following options best describes the most likely cause for the rash?

A. Infectious mononucleosis.
B. Allergic drug reaction.
C. Hypersensitivity vasculitis.
D. Varicella zoster infection.
E. Streptococcal pharyngitis.

Answer 14

B. Allergic drug reaction

A patient with suspected bacterial pharyngitis develops a rash after starting on amoxicillin. This often occurs when a patient with infectious mononucleosis (IM) is misdiagnosed and treated with antibiotics.

• Cause: Epstein–Barr virus
• Common Ages: 10-35 years, peak incidence 15-25 years
• Symptoms:
  
  • Sore throat
  • Lymphadenopathy (swollen lymph nodes)
  • Fever
  • Rash
  • Hepatosplenomegaly (enlarged liver and spleen)
• Incubation Period: 4-6 weeks

• Initial Rash:
  
  • Occurs in ~5% of cases
  • Pinkish, maculopapular (similar to rubella)
  • Blanching and non-pruritic (not itchy)
• Rash After Antibiotics:
  
  • 90-100% of patients given ampicillin or amoxicillin develop a rash
  • Non-blanching and itchy
  • Develops 5-9 days after starting antibiotics

• Allergic Reaction to Antibiotics:
  
  • Common in IM patients treated with amoxicillin
  • Non-blanching, itchy rash
  • Appears 5-9 days after starting the antibiotic
• Other Considerations:
  
  • Varicella Zoster: Vesicular, pruritic rash (no indication in this scenario)
  • Streptococcal Pharyngitis: Scarlatiniform rash (blanching, papular, erythematous within 2 days)

• Amoxicillin in IM: High likelihood of rash due to drug reaction.
• Immediate Action: Stop the antibiotic.
• Evaluation: Check for IM and avoid using similar antibiotics in the future.

By understanding the typical presentations and timing of rashes associated with IM and antibiotic use, you can better identify and manage allergic drug reactions.

The scenario describes a rather common clinical situation: a patient with suspected bacterial pharyngitis develops rash after being started on amoxicillin. This occurs when a patient with infectious mononucleosis is misdiagnosed as bacterial pharyngitis and started on antibiotics.
Infectious mononucleosis (IM) is a febrile illness caused by Epstein–Barr virus from herpes family. It can mimic diseases such as primay HIV infection, streptococcal tonsillitis, viral hepatitis and acute lymphatic leukemia. It may occur at any age but is more common between10 and 35 years with the peak incidence among those ages 15-25 years.
IM has an incubation period of 4-6 weeks. The disease may initially present with sore throat (the cardinal finding), lymphadenopathy, fever, rash, and hepatosplenomegaly.
The rash of IM is almost always related to antibiotics given for tonsillitis. The primary rash, most often non-specific, pinkish and maculopapular (similar to that of rubella), occurs in only about 5% of cases. It is usually blanching and non-pruritic.
About 90–100% of patients prescribed ampicillin or amoxycillin will be affected. This rash is non-blanching and itchy, and develops 5-9 days after antibiotics are started.
The rash of this patient is most likely to be an allergic reaction to the antibiotic. The exact mechanism of rash following administration of antibiotics in IM is not fully understood.
As mentioned earlier, the rash of IM presents early in the course of the disease. It has a faint color, and is non-pruritic and non-blanching in contrast to the rash here which is non-blanching and itchy.
Neither the initial rash of IM nor the drug-related rash developing after antibiotics are given are not caused by hypersensitivity vasculitis.
Varicella zoster infection presents with vesicular rash that is pruritic. There is no hint regarding varicella zoster as a cause in the scenario.
Streptococcal pharyngitis can be associted with scarlatiniform form rash (similar to the rash in scarlet fever) which might resemble the rash of this patiet. In a suspetible patient, this rash manifests within the first 2 days of symptoms and cause a papular, blanching and erythematous rash. This patient has developed an itchy, non-blanching rash 6 days after the onset of symptoms that makes such diagnosis less likely.

Question 15

A 16-year-old boy presents with a rash shown in the following photograph. The rash developed few days after he was started on amoxicillin-clavulanate and paracetamol because of sore throat, fever and cervical lymphadenopathy. He mentions no improvement despite being on antibiotic. Which one of the following is the most appropriate next step in management?

A. Add gentamicin.
B. Add erythromycin.
C. Stop the antibiotic.
D. Wait and watch.
E. Give systemic corticosteroids.

Answer 15

C. Stop the antibiotic

This occurs when a patient with Ebstein-Barr infectious mononucleosis is misdiagnosed as having bacterial pharyngitis and started on antibiotics accordingly in the majority of patients.
Infectious mononucleosis (IM) is a febrile illness caused by the herpes (Epstein–Barr) virus. It can mimic diseases such as HIV primary infection, streptococcal tonsillitis, viral hepatitis and acute lymphatic leukaemia. It may occur at any age but usually between 10 and 35 years; it is commonest in 15–25 years age group.
It has a incubation period of 4-6 weeks. The disease may present initially with sore throat (the cardinal finding), lymphadenopathy, fever, rash, hepatosplenomegaly, etc. There might be exudative tonsillitis resembling that of streptococcal pharyngitis. The rash of IM is almost always related to antibiotics given for tonsillitis when it is mistakenly considered bacterial.
The rash develops 5-9 days after antibiotics are started.
There could be another possible cause to the rash: a genuine delayed hypersensitivity reaction to amoxicillin-clavulanate, meaning that the patient has developed a genuine allergy to the antibiotic rather than an interaction with the underlying infection.
No matter if the rash is a result of interaction between the antibiotic and IM or a drug eruption caused by a genuine drug allergy, the next step in management is cessation of the culprit antibiotic, which is the amoxicillin – clavulanate here. Systemic steroids are the treatment of last resort for bothersome rashes not responding to more conservative treatments such as antihistamines.

C. Stop the antibiotic

The patient likely has infectious mononucleosis (IM) caused by the Epstein-Barr virus, but it was misdiagnosed as bacterial pharyngitis and treated with antibiotics.

1. Infectious Mononucleosis (IM):
   
   • Cause: Epstein-Barr virus.
   • Age Group: Common in ages 15-25.
   • Incubation Period: 4-6 weeks.
   • Symptoms: Sore throat, lymphadenopathy, fever, rash, hepatosplenomegaly.
   • Tonsillitis: Often exudative, resembling streptococcal pharyngitis.
2. Rash in IM:
   
   • Timing: Develops 5-9 days after starting antibiotics.
   • Cause: Usually due to antibiotics given for mistaken bacterial infection.
3. Possible Causes of Rash:
   
   • Interaction: Between antibiotic and Epstein-Barr virus.
   • Drug Allergy: A genuine allergic reaction to the antibiotic.
4. Management:
   
   • Stop the antibiotic: Regardless of the cause, stopping amoxicillin-clavulanate is essential.
   • Alternative Treatments: If the rash is severe and not responding to conservative treatments like antihistamines, systemic steroids may be considered.

When a rash develops in a patient with infectious mononucleosis after starting antibiotics, the primary management step is to stop the antibiotic. This helps address whether the rash is due to the interaction with the Epstein-Barr virus or a genuine drug allergy.

Question 16

A 30-year-old man presented to your GP office with complaints of acute sore throat and a fever of 39.2°C which developed 48 hours prior to his visit. On examination, he had red swollen tonsils with exudate. He was prescribed amoxicillin. After 5 days, he presents with a non-blanching pruritic rash all over body. The rash is shown in the following photograph. Which one of the following tests could be most diagnostic at this stage?

A. Penicillin allergy test.
B. Blood culture.
C. Full blood count.
D. Throat swabs and cultures.
E. Serologic tests for EBV.

Answer 16

C. Full blood count

Epstein-Barr Infectious Mononucleosis (IM)

Scenario:
This scenario often occurs when Epstein-Barr Infectious Mononucleosis (IM) is misdiagnosed as streptococcal pharyngitis and the patient is given aminopenicillins (e.g., amoxicillin, ampicillin).

Key Points:
- Cause: Epstein-Barr virus (herpes family).
- Common Age: 10-35 years (most common between 15-25 years).
- Incubation Period: 4-6 weeks.
- Symptoms: Sore throat (cardinal finding), lymphadenopathy, fever, rash (especially after starting antibiotics), and hepatosplenomegaly. The exudative tonsillitis may resemble streptococcal pharyngitis.

Diagnosis:
- Full Blood Count (FBC):
- Most Appropriate Initial Test: Invariably shows lymphocytosis (>50% lymphocytes).
- Blood Film: Shows atypical lymphocytes (>10% lymphocytes).

• Diagnostic Tests for IM:
  
  • Monospot® Test: Detects heterophile antibodies (reaction with horse red blood cells). More commonly used and preferred over serologic tests.
  • Paul-Bunnell Test: Traditional test (reaction with sheep red blood cells).
• Additional Information:
  
  • Serologic Tests (IgG and IgM against Epstein-Barr): Rarely needed unless Monospot® test is negative but clinical suspicion remains high. Performed weekly for six weeks if necessary.
  • Blood Cultures and Throat Swabs: Not useful for diagnosing IM as they are typically negative in this condition.

Clinical Application:
- Patient with Rash After Antibiotics: Consider IM if there is unresponsiveness to antibiotics and rash development. Perform an FBC to check for lymphocytosis.
- Further Management: Confirm diagnosis with Monospot® test if needed.

Conclusion:
The most appropriate initial test for a patient suspected of having Epstein-Barr Infectious Mononucleosis, especially after the development of a rash post-antibiotics, is a full blood count (FBC).

The scenario can be frequently encountered when Epstein-Barr infectious mononucleosis is misdiagnosed as streptococcal pharyngitis and the patient is started on aminopenicillins i.e. amoxicillin and ampicillin.
Epstein-Barr Infectious mononucleosis (IM) is a febrile illness caused by Epstein–Barr virus from herpes family. It can mimic diseases such as primary HIV infection, streptococcal tonsillitis, viral hepatitis and acute lymphocytic leukemia. It may occur at any age but usually between 10 and 35 years (most common between 15 and 25 years).
After an incubation period of 4-6 weeks, IM may present with sore throat (the cardinal finding), lymphadenopathy, fever, rash, and hepatosplenomegaly. There might be exudative tonsillitis resembling streptococcal pharyngitis. The rash develops 5-9 days after antibiotics are started.
With the rash and unresponsiveness to antibiotics, Epstein-Barr IM should be considered and investigated as the most likely cause.
Of the options, a full blood count, is the most appropriate test; however, not the most diagnostic one. In IM, the FBC will invariably demonstrate lymphocytosis (>50% lymphocytes). Lymphocytosis is a rule in IM. With normal or decreased lymphocyte count, a different diagnosis should be considered. Blood film will show atypical lymphocytes (>10% lymphocytes).
Diagnostic tests for Epstein-Barr IM are traditional Paul-Bunnell test (reaction of heterophile antibodies with sheep red blood cells) or the newer Monospot®® test (reaction of heterophile antibodies with horse red blood cells).
With Monospot® test available, serological studies (IgG and IgM titres against Epstein-Barr) are rarely indicated and only reserved for patients with signs and symptoms suggestive of the infection but with negative Monospot test results performed weekly for six weeks. Blood cultures and cultures of throat swabs are very unlikely to be positive if the cause is IM. They are not useful or indicated in this situation. Blood cultures are negative in IM and have no diagnostic value.
Throat swabs and cultures are negative in IM. They are not appropriate diagnostic tests to consider for patients with IM.
Serologic tests, so early in the course of the disease, are less likely to be diagnostic.Moreover, they are not clinically indicated because Monospot® test is more available and diagnostic.

Question 17

A 47-year-old man presents with complaints of swinging fevers, productive cough with a fetid odor and right-sided chest pain that worsens with respiration. These have occurred and progressed over a course of few days. A chest X-ray is obtained that shows a round opacity in the right middle lobe. There is air-fluid level within the opacity. Expectorated sputum is sent for gram stain and culture. The initial result of the Gram stain test reveals Staphylococcus aureus in the sputum. You start the patient on intravenous flucloxacillin. Which one of the following is could be the most appropriate next step in management?

A. Transpleural drainage.
B. Lobectomy.
C. Transcutaneous aspiration.
D. Water-sealed chest drain.
E. CT scan of the chest.

Answer 17

E. CT scan of the chest

• Clinical Presentation:
  
  • Right middle lobe opacity with air-fluid level suggests lung cavitation.
  • Symptoms: fever, productive cough (often foul-smelling), night sweats, weight loss, and malaise.
  • Often seen in an indolent course over days to weeks or months.
• Possible Causes:
  
  • Microbial infections (e.g., Staphylococcus aureus, Klebsiella pneumoniae, etc.).
  • Non-microbial causes like pulmonary infarction, bronchiectasis, necrotizing carcinoma, etc.
• Characteristics:
  
  • Lung abscess appears as a cavity in the lung, often visible on chest X-ray or CT scan.
  • Staphylococcus aureus can cause severe pneumonia, especially after influenza infection, presenting with shock and lung necrosis.

1. Chest X-Ray: Initial imaging to identify the presence of a lung abscess.
2. CT Scan of the Chest: Provides better anatomical detail and helps in differentiating between lung abscess and empyema.

• Uncomplicated Lung Abscess:
  
  • Antibiotics (often intravenously) are the main treatment, especially if the abscess communicates with the airway and drains spontaneously.
• Complicated Lung Abscess:
  
  • Criteria for Complication:
    
    • Failure to respond to medical management.
    • Suspected neoplasm.
    • Associated with an obstructed bronchus.
    • Extremely large abscess (>6 cm).
    • Involvement of resistant organisms like Pseudomonas aeruginosa.
  • Management Options:
    
    • Lobectomy or Pneumonectomy: Surgical removal of the affected lung lobe or entire lung.
    • Endoscopic or Percutaneous Drainage: Alternative for those who are poor surgical candidates.
      
      • Requires careful handling to avoid contamination of the pleural space.
      • Bronchoscopy can be used for diagnosis but is less effective for drainage.

• Aspiration for Sample: Not needed as the etiologic agent is already identified.
• Water-Sealed Chest Drain: Used for empyema, not for lung abscess without complications.

• Immediate Step: Perform a CT scan of the chest to confirm the diagnosis and assess the extent of the lung abscess.
• Follow-Up: Begin appropriate antibiotic treatment and consider surgical options if the abscess is complicated.

The clinical presentation as well as the radiographic finding of right middle lobe opacity with an air-fluid level is highly suggestive of lung cavitation. Lung abscess is a common cause of cavitation in lung parenchyma. Other pulmonary lesions that are not caused by microbes may resemble lung abscess. These include:
-Lesions of pulmonary infarction
-Bronchiectasis
-Necrotizing carcinoma
-Pulmonary sequestration
-Vasculitides e.g. polyarteritis nodosa, granulomatosis with polyangiitis (Wegener’s), Goodpasture syndrome –Cysts or bullae with fluid collections

The following organisms are capable of producing monomicrobial lung abscess:
-Staphylococcus aureus
-Klebsiella pneumoniae
-Gram negative bacilli
-Hemophilus influenza type B
-Legionella
-Nocardia Actinomycosis

Lung abscess can present with the following features:
An indolent course over days to weeks (or months in specific situations)
-Fever (rigors or chills are often absent)
-Productive cough that can be foul-smelling
-Night sweats
-Weight loss
-Malaise

The most characteristic form of pneumonia caused by Staphylococcus aureus is fulminant disease in young adults or adolescents with underlying influenza infection. The patient often has a fulminant course with shock, neutropenia, lung necrosis and high mortality rate despite antibiotic treatment.
Antibiotics (often intravenously) are mainstay of therapy for uncomplicated lung abscess, especially for those with air-fluid level that indicates communication of the abscess with airway and spontaneous abscess drainage. Surgical intervention is reserved for patients with complicated lung abscess. The following are considered as complicated lung abscess:
Failure to respond to medical management
Suspected neoplasm
Abscesses associated with an obstructed bronchus
An extremely large abscess (>6 cm in diameter)
Abscesses involving relatively resistant organisms such as Pseudomonas aeruginosa

The usual procedure in such cases is a lobectomy or pneumonectomy. For those who are poor candidates for surgery alternative methods such as endoscopic drainage or percutaneous drainage may be considered. Percutaneous procedures require special care to prevent contamination of the pleural space. Bronchoscopy may be done as a diagnostic procedure, especially to detect an underlying lesion, but this procedure is of relatively little use to facilitate drainage and can result in spillage of abscess contents into the airways. Endoscopic drainage, which requires an experienced operator, is performed by placing a pigtail catheter into the abscess cavity under bronchoscopic visualization and leaving the catheter in place until the cavity has drained.

Radiographic evaluation for differentia diagnoses or associated conditions
A chest X-ray generally demonstrates the pulmonary lesion to the extent necessary for diagnosis and management; however, better anatomic definition can be achieved with CT scanning. CT is particularly helpful if the diagnosis and delineation of the cavity is in doubt or in distinguishing between lung abscess and empyema despite looking similar on X-ray sometimes, require completely different managements.
However, if CT scan found the cause to be an empyema and not an abscess, transpleural drainage will be indicated.
Lobectomy (preferred) and transpleural drainage can be considered if the abscess is complicated, evident by the size, poor response to treatment, obstruction, etc. There is no clue in the scenario pointing towards complications; therefore, these measures are not appropriate for now.
The etiologic agent in this patient has already been determined by sputum exam so aspiration to obtain a sample is not appropriate or useful.
Water-sealed chest drain is a treatment option for empyema either in isolation or as a complication of lung abscess. There is no indication for that at present.

Question 18

Rob is a 30-year-old patient of yours, who was found to be HIV positive a while back. He was started on antiretroviral therapy after a consultation with an infectious disease specialist. Today, he is in your office for a follow-up visit. He looks quite calm and avoiding. After breaking the ice, you realize that he has been feeling down and has not taken his medications for the past 6 months. You arrange for laboratory tests, the results of which shows a decreased CD4 count of 46/mm3. You talk him into restarting his anti HIV medications. He is convinced to follow your instructions. In addition to the anti HIV medications, which one of the drug(s) he should receive?

A. Fluconazole.
B. Azithromycin and trimethoprim-sulfamethoxazole.
C. Dapsone.
D. Azithromycin and fluconazole.
E. Azithromycin, dapsone, and fluconazole.

Answer 18

B. Azithromycin and trimethoprim-sulfamethoxazole

HIV and CD4 Cells:
- HIV primarily infects CD4 T lymphocytes.
- A healthy person has a CD4 count around 700/mm³.
- HIV reduces CD4 count by 50-100/mm³ per year.
- Opportunistic infections typically occur when CD4 count drops below 200/mm³.

Common Opportunistic Infections:
- Pneumocystis jiroveci pneumonia (PCP)
- Toxoplasmosis
- Mycobacterium avium complex (MAC)

Prophylaxis Based on CD4 Count:
1. Pneumocystis jiroveci (CD4 < 200/mm³)
- Prophylactic Treatment: Trimethoprim-sulfamethoxazole (double-strength tablet daily)

2. Toxoplasmosis (CD4 < 100/mm³)
   
   • Prophylactic Treatment: Trimethoprim-sulfamethoxazole (double-strength tablet daily)
3. Mycobacterium avium complex (MAC) (CD4 < 50/mm³)
   
   • Prophylactic Treatment: Azithromycin (1200 mg weekly)

Example Scenario:
- Patient CD4 Count: 46/mm³
- Prophylactic Regimen Needed:
- Trimethoprim-sulfamethoxazole for PCP and Toxoplasmosis.
- Azithromycin for MAC.

• PCP and Toxoplasmosis: Trimethoprim-sulfamethoxazole
• MAC: Azithromycin

• Dapsone: Alternative to trimethoprim-sulfamethoxazole if intolerant.
• Fluconazole: Used for treating candidiasis, not for routine prophylaxis.

Given the patient’s CD4 count of 46/mm³, they should start prophylaxis with both trimethoprim-sulfamethoxazole (for PCP and Toxoplasmosis) and azithromycin (for MAC) along with their antiretroviral therapy.

The primary mechanism of HIV is infecting a particular subset of T lymphocytes known as CD4. Decreased amount of CD4 cells results in development opportunistic infections that define AIDS.
CD4 count in a non-infected person is approximately 700/mm3. HIV infection causes this number to drop at a rate of 50-100/mm3/year; therefore, without treatment, it would take 5-10 years for CD4 count to drop to around 200/mm3 when the first AIDS-defining syndrome develops.
An HIV infected person does not develop opportunistic infection unless CD4 decrease below a certain level; therefore, prophylactic treatment against such infections is not indicated as long as the CD4 count is above the predicted CD4 count for that infection.

The most common opportunistic infections associated with HIV infection include:
-Pneumocystis jiroveci (formerly carini)
-Mycobacterium avium complex (MAC)
-Toxoplasmosis
-Candidiasis
-Cryptococcosis Coccidioidomycosis
-CMV
-Tuberculosis
-Histoplasmosis
-Cryptosporidium

Of these infections, routine prophylactic is indicated for pneumocystis jiroveci, toxoplasmosis, and mycobacterium avium complex once CD4 count drops below 200/mm3, 100/mm3, and 50/mm3, respectively.

The following table summarizes the opportunistic infections in HIV infected patients and the CD4 count below which prophylaxis is commenced as well as the appropriate prophylactic regimen:
Routine prophylaxis for the following infections is not routinely indicated, unless there are indications other than CD4 count:
Candidiasis Cryptococcosis Coccidioidomycosis CMV
Tuberculosis Histoplasmosis Cryptosporidium
With a CD4 count of 46/mm3, this patient should be started on routine prophylaxis against pneumocystis jiroveci, toxoplasmosis, and mycobacterium avium complex. For this purpose, combination of trimethoprim-sulfamethoxazole and azithromycin should be considered in addition to antiretroviral therapy.

Pneumocystis jiroveci (formerly carini) - CD4 : 200 - Prophylactic recommendation: Trimethoprim-sulfamethoxazole (double-strength tablet daily)

Toxoplasmosis - CD4: 100 - Recommendation : Trimethoprim-sulfamethoxazole (double-strength tablet daily)

Mycobacterium avium complex - CD4 : 50 - Recommendation: Azithromycin (1200 mg weekly)

Dapsone can be replaced with trimethoprim-sulfamethoxazole as second-line medication, where the former cannot be tolerated or is contraindicated. Fluconazole is used for treatment of Candidiasis (oropharyngeal, vaginal, esophageal) and has no role in routine prophylaxis.

Question 19

A 2-year-old boy is brought to your GP clinic with drowsiness, fever and a petechial rash. You suspect meningitis based on clinical grounds. Which one of the following is the most appropriate next step in management?

A. Blood culture.
B. Intravenous access.
C. Lumbar puncture.
D. Intravenous ceftriaxone.
E. Intravenous benzylpenicillin.

Answer 19

B. intravenous access

The presence of rash and fever is highly suggestive of meningococcemia. In approach to an ill child with suspected bacterial meningitis in settings other than hospital, the most important step in management is supplemental oxygen and intravenous (IV) access. Although there is no comment in the scenario regarding hemodynamic compromise, such children are susceptible to rapid deterioration and collapse. A bolus dose of 20ml/kg (up to 60ml/kg) should be given intravenously. If IV access cannot be established, interosseous route should be tried.
Parenteral benzylpenicillin is an appropriate option as it is readily available; however, since other invasive pathogens such as Streptococcus pneumoniae and Hemophilus influenza type b can cause invasive disease with similar presentation, a broader spectrum antibiotic such as ceftriaxone or cefotaxime is preferred if available. In case of hypersensitivity to cephalosporins or penicillins, chloramphenicol is recommended. Intravenous administration is the preferred route.
Blood sample for culture should also be obtained if possible when intravenous access is tried. If not, antibiotics should not be delayed.
Lumbar puncture should be performed in the hospital in consultation with an expert in the field.

Question 20

An 75-year-old man presents to your GP clinic with complaints of dysuria, frequency and urgency. Investigations, including urine analysis establish the diagnosis of urinary tract infection (UTI). His GFR is 17 ml/min. Which one of the following is the antibiotic of choice for treatment of his UTI?

A. Amoxicillin.
B. Gentamicin.
C. Ciprofloxacin.
D. Trimethoprim.
E. Nitrofurantoin.

Answer 20

D. Trimethoprim

The choice of antibiotics for management of pyelonephritis in patients with decreased GFR is generally the same for patients with normal GFR, but dose adjustment according to the GFR is often required. For empiric treatment of UTI in men, while awaiting the results of the investigations, trimethoprim is the antibiotic of choice.
UTI in men is often associated with an underlying urinary tract anomaly. The duration of antibiotic therapy for UTI in men is 14 days.
Amoxicillin is never used for empiric treatment of UTI because the very high rates of resistance to this antibiotic.
Gentamicin is not among recommended options for empiric treatment of uncomplicated UTI. Moreover, aminoglycosides such as gentamicin are nephrotoxic.
Fluoroquinolones (e.g. ciprofloxacin) should not be used as first-line therapy as they are the only active drugs available for infections due to Pseudomonas aeruginosa and other multiresistant bacteria. Nitrofurantoin can also be used as an alternative, but is not recommended as first-line option. This is true about cephalexin and amoxycillin +clavulanate.

Question 21

A 5-year-old boy is brought to the emergency department with lethargy and a fever. On examination, he has neck stiffness. With meningitis as the most likely diagnosis, a lumbar puncture is performed, the result of which is as follows:
Opening pressure: 45mmH2O (5-20) Appearance: cloudy
Protein: 1.2g/L (0.18-0.45)
Glucose: 1.5mmol/L (2.5-3.5)
WCC: 900/mm3 (<3) neutrophil predominance
The child is started on intravenous cefotaxime. Which one of the following should be considered as the most appropriate next step in management?

A. Oral paracetamol.
B. Aspirin.
C. Intravenous dexamethasone.
D. Acyclovir.
E. CT scan of the head.

Answer 21

C. Intravenous dexamethasone

Here are the key concepts for managing suspected bacterial meningitis in children:

1. Lumbar Puncture (LP):
   
   • Perform an LP before starting antibiotics if possible to analyze cerebrospinal fluid (CSF).
   • CSF findings in bacterial meningitis typically include high protein, low glucose, and increased white cell count with neutrophil predominance.
2. Immediate Antibiotic Therapy:
   
   • Start intravenous antibiotics immediately if bacterial meningitis is suspected, ideally after taking blood cultures.
3. Dexamethasone:
   
   • For children over 2 months old, administer dexamethasone (0.15 mg/kg IV) before or within one hour of starting antibiotics to reduce the risk of hearing loss.
4. Paracetamol for Fever:
   
   • Paracetamol can be used to lower fever, but administering dexamethasone is more critical.
5. Avoid Aspirin:
   
   • Do not use aspirin in febrile children due to the risk of Reye syndrome.
6. Antivirals:
   
   • Only consider antiviral agents like acyclovir if there are clinical or laboratory signs of viral encephalitis, which include altered mental state and focal neurological findings.
7. CT Scan:
   
   • A CT scan before LP is not routine in children unless there’s a concern about increased intracranial pressure. If the LP has already been performed, a CT scan is not typically needed.

By following these key concepts, healthcare providers can effectively manage suspected bacterial meningitis in children and reduce the risk of complications.

If possible, an LP should be performed prior to starting antibiotics in suspected cases of meningitis. This child has a CSF analysis consistent with the diagnosis of bacterial meningitis. High protein, low glucose and increased WCC with neutrophil predominance make bacterial meningitis the most likely diagnosis with high certainty.
Once, on clinical grounds and/or CSF analysis results, bacterial meningitis is suspected, intravenous antibiotics should be started as the most appropriate step management, ideally after blood samples are taken for culture.
Current evidence suggests that steroids may reduce the risk of hearing loss in bacterial meningitis. For children >2months of age, dexamethasone (0.15mg/kg, intravenously) should be administered before antibiotics or within one hour of commencement of antibiotics.
Paracetamol may be considered to lower the fever in a febrile child; however, this does not take precedence over dexamethasone.
Aspirin is not used in febrile children to the risk of Reye syndrome.
Acyclovir or other antiviral agents are indicated if ,based on clinical and/or laboratory findings, viral encephalitis is suspected. The CSF analysis in this child is not suggestive of a viral etiology, nor are there comments about confusion, altered mental state or focal neurological findings as is expected in encephalitis.
CT scan of the head may be considered for adults before LP is attempted to exclude increased intracranial pressure that can result in brain herniation once LP is performed. It is not a routine practice in children. Moreover, in this child LP has already been carried out and there is not further indication for CT scanning.

Question 22

A 46-year-old woman presents to the emergency department with headache and photophobia. Lumbar puncture is performed after CT scan of the head excluded increased intracranial pressure.
The CSF analysis result is as follows:
Opening pressure 25cmH2O (normal:10-20)
WCC: 40/mm3 – lymphocytes 85%
Total protein: 1.8 g/L (normal: 0.15-0.45)
Glucose: 1.0 mmol/L (2.5-3.5) Simultaneous serum glucose: 4.9 mmol/L
Which one of the following is the least likely diagnosis?

A. Partly treated bacterial meningitis.
B. Carcinomatosis meningitis.
C. Viral meningitis.
D. TB meningitis.
E. Fungal meningitis.

Answer 22

C. Viral meningitis

Diagnosing Meningitis: Key Points Simplified

1. Normal CSF Glucose:
   
   • 2.5-3.5 mmol/L or 60-80% of plasma glucose.
2. Decreased CSF Glucose:
   
   • Common in: Bacterial, TB, fungal, and carcinomatosis meningitis.
   • Uncommon in: Viral meningitis (except mumps, enteroviruses, herpes can cause mild decrease).
3. CSF Glucose in Patient:
   
   • 1.0 mmol/L, 20% of serum glucose = Unlikely viral meningitis.
4. Elevated CSF Protein:
   
   • Common in: Bacterial, TB, fungal, carcinomatosis meningitis.
   • Uncommon in: Viral meningitis (usually <1g/L, can be normal).
5. CSF Protein in Patient:
   
   • Elevated = Suggests bacterial, TB, fungal, or carcinomatosis meningitis.
6. CSF Opening Pressure:
   
   • Increased in: Bacterial meningitis.
   • Normal or slightly raised in: Viral meningitis.
7. CSF Opening Pressure in Patient:
   
   • 25 cmH2O = More likely bacterial meningitis.

1. 5-100/mm³:
   
   • Early bacterial, viral, TB meningitis, encephalitis.
2. 100-1000/mm³:
   
   • Bacterial, viral, TB meningitis, encephalitis.
3. >1000/mm³:
   
   • Bacterial meningitis, mumps, lymphocytic choriomeningitis.
4. CSF WCC in Patient:
   
   • 40/mm³ = Could be early bacterial, viral, fungal, or TB meningitis.

1. Bacterial Meningitis:
   
   • Decreased glucose.
   • Elevated protein.
   • High opening pressure.
2. TB or Fungal Meningitis:
   
   • Similar findings to bacterial meningitis.
   • Decreased glucose.
   • Elevated protein.
   • Varied cell counts.
3. Carcinomatosis Meningitis:
   
   • Rare.
   • Decreased glucose.
   • Elevated protein.
   • No cancer history in patient makes it less likely.

• Viral Meningitis:
  
  • Normal or slightly decreased glucose.
  • Normal or slightly elevated protein.
  • Normal or slightly increased opening pressure.

• With decreased glucose, elevated protein, and high opening pressure, bacterial meningitis is the most likely diagnosis. Viral meningitis is the least likely due to the CSF findings.

• Bacterial: Low glucose, high protein, high pressure.
• Viral: Normal glucose, normal/low protein, normal/slightly high pressure.
• TB/Fungal: Similar to bacterial but consider travel history, immune status.
• Carcinomatosis: Rare, consider cancer history.

Normal concentration of glucose in CSF samples is 2.5-3.5 mmol/L, or 60-80% of simultaneous plasma glucose (for glucose plasma concentrations less than 22 mmol/L). A significant decrease CSF glucose level, especially decreased CSF glucose level in relation with serum are usually associated with bacterial, TB, fungal and carcinomatosis meningitis, but not viral meningitis.
Exceptionally, viral meningoencephalitis caused by mumps, enteroviruses, herpes simplex and herpes zoster can be associated with mild to moderate decrease in CSF glucose; however, a CSF glucose of 1.0 mmol/L and a CSF-to-serum glucose ratio of 20% (normal 60-80%) is very unlikely to be caused by viral meningitis.
This patient has also an elevated CSF protein level. Typically, protein level is elevated in bacterial, TB, fungal and carcinomatosis meningitides, but decreased in viral meningitis (often <1g/L) but it can be normal as well. An elevated protein level in this patient’s CSF makes viral meningitis less likely than bacterial, fungal or TB meningitides (but not unlikely).
Finally, the CSF opening pressure in this patient has been 25 cmH2O. Increased opening pressure is more commonly seen in bacterial rather than viral meningitis. In viral meningitis, the opening pressure is normal or just slightly raised above normal. A normal opening pressure does not exclude bacterial meningitis though.
With a significantly decreased CSF glucose, high protein level and elevated CSF opening pressure, viral meningitis is the LEAST likely diagnosis.
The cell count is not of much help to exclude a causative agent as there is a huge overlap between different types of meningitis in terms of cell count. Interpretation of total white cells in CSF is summarized in the following table:
5-100/mm3 :
Early bacterial meningitis
Viral meningitis
TB meningitis
Encephalitis

100-1000/mm3
Bacterial meningitis
Viral meningitis
TB meningitis
Encephalitis

> 1000/mm3
Bacterial meningitis
Mumps, lymphocytic choriomeningitis

The WCC of this patient does not make any of the options least likely. A WCC count of 40/mm3 may be due to early bacterial meningitis, viral meningitis, fungal meningitis or TB meningitis.
In patients with partly treated bacterial meningitisو culture and Gram stain results may be altered (less frequently positive), but other CSF values such as cell count, protein and glucose remain mostly unchanged. With elevated CSF protein and decreased CSF glucose, bacterial meningitis can be likely despite a WCC count of 40 with lymphocytic predominance.
Carcinomatosis meningitis is a rare complication of cancer in which the disease spreads to the meninges. It occurs in 5% of patients with cancer, usually terminal. With treatment, median survival is 2-3 months. CSF analysis shows decreased glucose and elevated protein levels as in this patient. However, no cancer in the history and the rarity of the condition make it less likely.

CSF in fungal/TB meningitis often has decreased glucose, increased protein and cell count of 5-100 up to 500 cell/mm3. This patient can have either of them based on given CSF findings.

Question 23

A 35-year-old woman presents to your practice with a painful tender swelling inferior to the medial side of his left eye. The lesion is shown in the following photograph. She is otherwise healthy and not febrile. Which one of the following is the most appropriate next step in management?
(page 678)

A. Massage and heat.
B. Intravenous dicloxacillin.
C. Incisionand drainage.
D. Oral amoxicillin.
E. Oral flucloxacillin.

Answer 23

E. Oral flucloxacillin

The pus-filled swelling below the medial canthus is highly suggestive of acute dacryocystitis. The surrounding skin is red but not significantly swollen. In most patient with acute dacryocystitis, antibiotics such as di/flucloxacillin, amoxicillin- clavulanate, or cephalexin are associate with a dramatic response, and should be used as first-line management options. Intravenous route is reserved for patients with severe cellulitis, orbital involvement (orbital cellulitis) or severe adjacent facial/periseptal cellulitis.
Massage and heat is used in patients with mild dacryocystitis. In more severe cases, massage is exquisitely painful and not effective.
This patient does not have orbital/periorbital cellulitis, significant facial cellulitis, or signs of systemic toxicity. In such cases intravenous antibiotics are unnecessary and oral route is very likely to provide adequate coverage and treatment. Incision and drainage is not recommended in active infection. However, it is rarely considered in very severe cases associated with serious complications such as orbital cellulitis or when more conservative management fails.

In most cases acute dacryocystitis is caused by complete obstruction of the nasolacrimal duct, preventing normal drainage from the lacrimal sac into the nose.
Clinical findings include edema and erythema with distension of the lacrimal sac below the medial canthal tendon. The degree of discomfort ranges from none to severe pain. Complications include dacryocystocele formation, chronic conjunctivitis, and spread to adjacent structures (orbital or periorbital/facial cellulitis).
Guidelines for treatment of acute dacryocystitis are as follows:
Avoid irrigation or probing of the canalicular system until the infection subsides. In most cases, irrigation is not needed to establish the diagnosis and is extremely painful in the setting of active infection. Similarly, diagnostic or therapeutic probing of the nasolacrimal duct is not indicated in adults with acute dacryocystitis.
Topical antibiotics are of limited value. They do not reach the site of the infection because of stasis within the lacrimal drainage system. They also do not penetrate sufficiently within the adjacent soft tissue.
Oral antibiotics are effective in most infections. Gram-positive bacteria are the most common cause of acute dacryocystitis. However, gram-negative organisms should be suspected in patients who are diabetic or immunocompromised or in those who have been exposed to atypical pathogens (e.g. individuals residing in nursing homes). Parenteral antibiotics are necessary for the treatment of severe cases, especially if cellulitis or orbital extension is present.
Incision and drainage of a localized abscess involving the lacrimal sac and adjacent soft tissues should be reserved for severe cases and those who are unresponsive to more conservative measures because a chronically draining epithelialized fistula that communicates with the lacrimal sac can form. The incised abscess is packed open and allowed to heal by second intention. This treatment should be reserved for severe cases and those that do not respond to more conservative measures.

Question 24

A 60-year-old man is booked for elective colonoscopy as a part of evaluation of iron deficiency anemia. He was diagnosed with mitral regurgitaion 15 years ago. Which one of the following is the next best step in management regarding infectious endocarditis prophylaxis?

A. Amoxicillin 2g before the procedure.
B. Ceftriaxone1g before the procedure.
C. No prophylaxis is needed.
D. Amoxicillin 500mg 6hours before the procedure.
E. Gentamicin 80mg before the procedure.

Answer 24

C. No prophylaxis needed

C. No prophylaxis needed

Antibiotic prophylaxis is recommended for certain cardiac conditions during specific procedures. The conditions include:

1. Prosthetic cardiac valve or material used for valve repair.
2. Previous infective endocarditis.
3. Congenital heart diseases:
   
   • Unrepaired cyanotic defects, including shunts and conduits.
   • Completely repaired defects with prosthetic material/devices within the first 6 months after the procedure.
   • Repaired defects with residual issues at/near the site of a prosthetic patch or device.
4. Cardiac transplantation with subsequent valvulopathy.
5. Rheumatic heart disease in Indigenous Australians only.

Mitral valve regurgitation does not require antibiotic prophylaxis for infective endocarditis.

• Prosthetic valves and previous endocarditis need prophylaxis.
• Specific congenital heart diseases need prophylaxis.
• Cardiac transplant patients with valvulopathy need prophylaxis.
• Indigenous Australians with rheumatic heart disease need prophylaxis.
• Mitral valve regurgitation does not need prophylaxis.

Antibiotic prophylaxis is recommended in patients with the following cardiac conditions who are undergoing a specific procedure:
1. Prosthetic cardiac valve or prosthetic material used for cardiac valve repair
2. Previous infective endocarditis
3. The following congenital heart diseases:
-Unrepaired cyanotic defects, including palliative shunts and conduits
-Completely repaired defects with prosthetic material or devices, whether placed by surgery or catheter intervention, during the first 6 months after the procedure (after which the prosthetic material is likely to have been endothelialized)
-Repaired defects with residual defects at or adjacent to the site of a prosthetic patch or device (which inhibit endothelialization)

4. Cardiac transplantation with the subsequent development of cardiac valvulopathy
5. Rheumatic heart disease in Indigenous Australians only

Mitral valve regurgitation is not an indication for infectious endocarditis prophylaxis.

Question 25

A 37-year-old man presents to your practice with complaints of fever and three episodes of loose stool since yesterday. He returned back from a four-day stay in Thailand two days ago. On examination, he has a fever of 38.7° with no other remarkable findings. A full blood exam (FBE) reveals no anemia. Which one of the following options excludes malaria as the diagnosis?

A. The short incubation period.
B. The fever.
C. The absence of splenomegaly.
D. The absence of anemia.
E. Diarrheal episodes.

Answer 25

A. The short incubation period

It is very important to consider malaria in all febrile returning travelers to areas where malaria is endemic. Following the bite of an infected female anopheles mosquito, the inoculated sporozoites go to the liver within 1-2 hours. The bitten individual is often asymptomatic for 12 to 35 days; however, symptoms can develop as early as 7 days. The incubation period for plasmodium falaciparum is 7; however, people who have taken antimalarial drugs or have partial immunity due to frequent exposures may develop symptoms much later. The incubation period for relapsing species plasmodium ovale and plasmodium vivax is approximately 2 weeks but clinical symptoms can occur months later due to activation of hypnozoites. The incubation period for plasmodium malariae is about 18 days.
This man has been in Thailand for four days and his symptoms have started one day after he has returned. Even if bitten on the first day the diagnosis cannot be malaria given the fact that the minimum reported incubation period for malaria is at least 7 days .
In malaria, fever is usually fluctuating and is associated with rigors, chills, and sweating.
In a non-immune person, the spleen can be palpable after several days of symptoms. Given these, a normal spleen, or the lack of anemia does not exclude malaria as the diagnosis.
Clinical malaria often starts with fever, malaise, fatigue, tachycardia, tachypnea, sweating, headache, cough, anorexia, nausea, vomiting, abdominal pain, diarrhea, arthragia and myalgia. Mild jaundice may also be present. Fluctuating fever is almost always a feature. Since diarrhea can be a manifestation, its presence does not exclude malaria.

In a person with malaria, laboratory findings other than anemia may include: thrombocytopenia, elevated transaminases, increased blood urea nitrogen (BUN) and creatinine, mild coagulopathy and hyperbilirubinemia (often indirect).

Question 26

A 32-year-old Sudanese man, who is a recent immigrant to Australia, presents for medical assessment. He has been febrile for the past two weeks, is lethargic and has decreased appetite. Laboratory tests are normal expect for mildly elevated WBCs of 12300/mm3. A chest X-ray is obtained which is shown in the following photograph. Which one of the most important initial step in management of this patient?

A. Commencement of treatment with doxycycline.
B. Isolation.
C. Monotherapy with isoniazid.
D. Quadruple therapy withr ifampin, isoniazid, pyrazinamide and ethambutol (RIPEtherapy).
E. Sputum smear and culture.

CXR cavitation right upper lobe

Answer 26

B. Isolation

The X-ray is remarkable for cavity formation in the upper lobe of the right lung. This X-ray finding and the symptoms of fever, lethargy and decreased appetite in a recently migrated patient from Sudan, makes pulmonary tuberculosis (TB) the most likely diagnosis.
TB is caused by the Mycobacterium tuberculosis (M. tuberculosis) complex.
A person with pulmonary TB is infectious as long as viable bacilli are being discharged from the sputum.The risk of transmitting infection is reduced within days to two weeks after starting TB treatment, providing there is no drug resistance.

A sputum smear-positive case is more infectious than a case that is only culture-positive.
Due to high degree of infectivity of pulmonary TB, it is strongly recommended that all suspected or definite cases of pulmonary TB be appropriately isolated regardless of being treated in outpatient and inpatient setting as the very first step in management while other investigations/treatment is undertaken.
A restriction order, e.g. under a Notifiable Diseases Act or similar, may be issued to a person with pulmonary TB who does not comply with prescribed treatment and is not willing to limit their movement within the community.

The criteria for discontinuation of isolation include:
For patients with suspected TB:
Infectious TB is subsequently considered unlikely and either:
an alternative diagnosis has been made which explains the clinical manifestations; or the patient has three consecutive negative AFB sputum smears on different days
For patients with confirmed TB:
The patient has been started on treatment and:
has received a minimum of two weeks of effective therapy; and
understands and tolerates the medications, and is improving clinically, including improvement of cough; or there are three consecutive daily negative sputum AFB smears.
patients with extra-pulmonary TB do not require isolation.

Doxycycline is not the standard treatment option for TB.
Monotherapy with isoniazid may be considered for patients with latent TB infection (LTBI). This regimen is not appropriate for active TB.
The initial (also called intensive) phase of TB treatment for patients with no suspected drug resistance is with four antibiotics i.e. rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE regimen). This treatment phase is often started before antibiotic sensitivity results are available. The duration of the initial intensive phase is for a minimum of two months or at least until sputum is smear negative for pulmonary TB and, in culture positive cases, drug susceptibilities are known, whichever is longer.
Sputum AFB smear, culture and sensitivity are mandatory and should be performed as soon as possible. However, isolation should be undertaken prior to any investigations or treatment in all cases with suspected or confirmed pulmonary TB.

Question 27

A 40-year-old man presents to the emergency department with complaints of fever and cough. He has the history of chronic cough and sputum for the past 2 years. According to him, the sputum is greenish-yellow and very copious especially in the morning. He mentions that he almost has had a cup-full of sputum every days for the past several months. On examination, he has a blood pressure of 110/95mmHg, pulse rate of 110bpm, temperature of 38.7, and O2 saturation of 92% while on room air. Lung auscultation reveals consolidation of the right lower lobe and bibasal crackles. A chest x-ray establish the diagnosis of lobar pneumonia. Which one of the following is the most appropriate treatment option for him?

A. Oral roxythromycin.
B. Oral Augmentin.
C. Intravenous ampicillin.
D. Intravenous flucloxacillin.
E. Intravenous piperacillin-tazobactam.

Answer 27

E. Intravenous piperacillin-tazobactam

Managing Lobar Pneumonia in a Patient with Bronchiectasis

A patient with chronic yellow-green sputum is likely suffering from bronchiectasis, a condition where the airways become permanently widened due to repeated infections. This condition often leads to frequent sputum production and infections.

Symptoms of Bronchiectasis:
- Persistent cough with daily mucus production (often for months or years)
- Blood-streaked sputum or hemoptysis (blood in sputum)
- Shortness of breath, chest pain, wheezing, fever, weakness, fatigue, and weight loss

Physical Exam Findings:
- Crackles, rhonchi, and wheezing sounds in the lungs
- Digital clubbing (enlarged fingertips) in some patients
- Rare signs like cyanosis (bluish skin) and plethora (red skin) due to chronic low oxygen levels
- Nasal polyps and chronic sinusitis
- Signs of cor pulmonale (right-sided heart failure)

Exacerbations of Bronchiectasis:
- Increased sputum production and thickening
- Malodorous sputum (sometimes)
- Low-grade fever (rare)
- Increased fatigue and shortness of breath
- Worsening chest pain and wheezing

Treatment for Exacerbations:
- Oral antibiotics like amoxicillin or doxycycline
- If Pseudomonas aeruginosa is present, use quinolones like ciprofloxacin or moxifloxacin

For Lobar Pneumonia Superimposed on Bronchiectasis:
- Lobar pneumonia requires stronger antibiotic treatment than bronchiectasis exacerbations.
- Many bronchiectasis patients have Pseudomonas aeruginosa infections.
- First-line antibiotics should cover Pseudomonas and include:
- Piperacillin-tazobactam (IV)
- Ceftazidime
- Meropenem
- Ticarcillin-clavulanic acid

Other Considerations:
- Oral antibiotics like roxithromycin or Augmentin are suitable for bronchiectasis exacerbations but not for lobar pneumonia.
- Ampicillin and flucloxacillin do not cover Pseudomonas adequately.

Summary:
For a patient with bronchiectasis who develops lobar pneumonia, the recommended treatment includes intravenous antibiotics such as piperacillin-tazobactam to cover potential Pseudomonas aeruginosa infections.

The chronic copious sputum production that is yellow-green in color is highly suggestive of bronchiectasis as the underlying lung condition, over which a lobar pneumonia has superimposed. Bronchiectasis is the irreversible dilation of one or more of the conducing bronchi or airways, most often secondary to an infectious process.

Bronchiectasis presents with the following:
-Cough and daily mucopurulent sputum production, often lasting months to years (classic)
-Blood-streaked sputum or hemoptysis from airway damage associated with acute infection
-Dyspnea, pleuritic chest pain, wheezing, fever, weakness, fatigue, and weight loss

Exam findings in a patient with bronchiectasis are often non-specific and include:
-Crackles, rhonchi, scattered wheezing, and inspiratory squeaks on auscultation
-Digital clubbing (2-3% of patients; more frequent in moderate-to-severe cases)
-Cyanosis and plethora with polycythemia from chronic hypoxia (rare)
-Wasting and weight loss
-Nasal polyps and signs of chronic sinusitis
-Physical stigmata of cor pulmonale, in advanced disease

Exacerbation of bronchiectasis is characterized by:
-Increased sputum production over baseline
-Thickening of the sputum
-Malodorous sputum (occasional)
-Low-grade fever (a rare finding)
-Increased fatigue
-Increased dyspnea, shortness of breath, wheezing, or pleuritic chest pain

Exacerbations of bronchiectasis often require oral antibiotic therapy with amoxicillin or doxycycline. Patients in whom pseudomonas aeroginosa is isolated from sputum culture require a quinolone such as ciprofloxacin or moxifloxacin to cover this organism.
This patient, however, has a lobar pneumonia that demands a different antibiotic therapy from that used for an exacerbation of bronchiectasis. It is estimated that a significant number of patients with bronchiectasis are colonized or have chronic infection with pseudomonas aeroginosa; therefore, for this patient an antibiotic with adequate coverage against this pathogen should be considered as first-line empiric therapy until susceptibility is available. Ceftazidime or a synthetic penicillins with anti-pseudomonas activity such as piperacillin + tazobactam or ticarcillin +clavulanic acid, or meropenem are first-line antibiotics to consider for this patient.
Oral roxythromycin (a macrolide) or oral Augmentin (amoxicillin + clavulanic acid) were appropriate options if the case was an exacerbation of bronchiectasis not pneumonia. Ampicillin and flucloxacillin do not provide adequate coverage against pseudomonas.

Question 28

A 25-year-old man presents to the emergency department of a tertiary hospital with complaint of back pain. The pain is felt over the L4/L5 region. He denies any history of preceding back trauma or sprain, but admits to injecting drug use previously. He also mentions positivity for hepatitis C virus antibody. Remarkable finding on physical examination is erythema and tenderness over the L4/L5 area. Which one of the following would be the most appropriate diagnostic approach to reach a diagnosis in this patient?

A. CT scan of the lumbar area.
B. MRI of the lumbar area.
C. HIV serology.
D. Bone scan.
E. X-ray of the lumbar area.

Answer 28

B. MRI of lumbar area

Local tenderness and erythema over a bony area in a patient with history of injection drug abuse should raise the suspicion of osteomyelitis as a very likely diagnosis.
This possibility is increased given the positive hepatitis C antibody titer that indicates hepatitis C infection and the likelihood of other infections associate with shared needle use. Needle sharing is associated with a significant risk of hematogenous spread of infections to bones, joints and soft tissue.
Osteomyelitis can occur as a result of contiguous spread of infection from adjacent soft tissue and joints, hematogenous seeding, or direct inoculation into the bone as a result of trauma or surgery. Hematogenous osteomyelitis is more common in children than in adults. In children, long bones are most often affected, while the vertebral column is the most common site of involvement with hematogenous spread in adults.
Typically, acute osteomyelitis presents with gradual onset of symptoms over several days. There is often dull pain in the affected area that can be related or unrelated to movement. There might be local findings such as erythema, swelling, tenderness or warmth, or systemic manifestations such as fever and rigors. However, patients with osteomyelitis of the hip, vertebrae or pelvis may have few signs and symptoms other than pain (such as in this patient).
MRI is the investigation of choice in diabetic patients with suspected osteomyelitis of the foot and all patients with suspected osteomyelitis of the vertebral column.

ESR and full blood exam are tests routinely consider but they are not specific. Findings associated with osteomyelitis are leukocytosis and elevated ESR (and often CRP) which are common findings in many other conditions than osteomyelitis.
An X-ray is the initial diagnostic modality to consider in patients presenting with signs and symptoms of osteomyelitis. X-rays however are usually negative and not sensitive in the first 2-3 weeks of infection. X-ray becomes positive when at least 50% of the mineral bone is lost due to infection.

*https://emedicine.medscape.com/article/1348767-overview
*https://www.uptodate.com/contents/approach-to-imaging-modalities-in-the-setting-of-suspected-osteomyelitis

Question 29

An indigenous woman has brought her three-year-old son to your GP clinic on the advice of an Aboriginal liaison in her community. She was diagnosed with pulmonary tuberculosis 13 months ago and was treated with standard quadruple therapy. She wants to know if her son may have contacted TB from her. On physical examination, the child has no symptoms. You order a Quantiferon-TB Gold test for the child, the result of which comes back positive. Which one of the following is the most appropriate next step in management of this child?

A. Start him on isoniazid.
B. Obtain a chest X-ray.
C. Repeat the Quantiferon-TB Gold test.
D. Start him on quadruple therapy.
E. Obtain sputum sample for acid fast bacilli microscopy and culture.

Answer 29

B. Obtain a chest X-ray

This child has been in close contact with a person with active TB (his mother), and there are chances that he also has contracted the infection. In fact, the positive Quantiferon-TB Gold test indicates that he has TB infection. The next question to answer is whether he has latent TB infection (LTBI) or active TB infection.
With a positive Quantiferon-TB Gold (IGRA) or tuberculin skin test (TST) [also termed as Mantoux test] in an asymptomatic patient, the next step is always obtaining a chest X-ray. If the chest X-ray is clear, the patient does not have active TB and should be treated for LTBI by monotherapy with isoniazid for 6-9 months.
If the chest X-ray shows abnormalities in favor of TB infection, the next is obtaining three sputum samples for acid fast bacilli (AFB) stain and culture. If all the three samples are negative, active TB infection is excluded and the patient should be treated for LTBI. With even one positive sample, active TB infection is the diagnosis, and the patient should be treated with standard quadruple therapy.
This child is asymptomatic and has a positive Quantiferon-TB Gold test. For him, obtaining an X-ray would be the most appropriate next step in management.
Starting the child on isoniazid alone for treatment of LTBI is considered if investigations, as outlined above, show he does not have active TB infection.
Quantiferon-TB Gold test has a very high specificity. Once it is positive, TB infection is almost certain, and there is no need for the test to be repeated.
Quadruple therapy with rifampicin, isoniazid, pyrazinamide and ethambutol (RIPE regimen) is used for treatment of active TB infection. Active TB is not an established diagnosis for this child yet. Obtaining sputum sample for acid fast bacilli (AFB) stain and culture would be the correct answer if the X-ray shows abnormalities that support TB as a diagnosis.

***READ PAGE 687 & 688 - longer topic review

Question 30

A 45-year-old man presents to your practice with complaints of fever, joint pain and a generalized rash all over his body. His fever and other symptoms started this morning, five days after he returned from Thailand. On examination, maculopapular rash over his limbs and trunk are noted. Despite generalized severe joint pain, no arthritis is noted on exam. Abdominal exam is normal and there is no lymphadenopathy. A full blood exam (FBE) is performed, the result of which is as follows:
Hb: 135 g/L (normal: 130-180 g/L)
RBC: 5x106/mm3 (4.5x106-6.5x106/ mm3)
MCV: 85 fL (76-96 fL)
WCC: 3100/mm3 (4000-11000/ mm3) Platelet: 75000/mm3 (150,000-400,000/mm3)
Which one of the following is the most likely diagnosis?

A. Malaria.
B. Leptospirosis.
C. Dengue fever.
D. HIV infection.
E. Infectious mononucleosis.

Answer 30

C. Dengue fever

The clinical findings of fever, arthralgia and a generalized rash, as well thrombocytopenia and leukopenia in a traveller to an endemic area is consistent with Dengue fever as the most likely diagnosis.

In its classic form, dengue fever is an acute febrile illness with the following manifestations:
Fever – 100%
Nauseas – 37%
Headache – 68%
Retro-orbital pain
Marked muscle and joint pains – the disease is sometimes called ‘break bone fever’.
Myalgia is seen in 79% of patients Rash
Sore throat

Fever typically lasts up to 7 days. The fever can be biphasic in a minority of patients. It subsides and then returns in about two days.

Typical rash of Dengue fever is similar to that of rubella. It starts on the limbs and progress to involve the trunk. In some patients petechial rash is present, even in the absence of thrombocytopenia. Hemorrhagic dengue fever is a rare form of the disease characterized by life-threatening hemorrhage. A 2-5 times rise in AST is in a frequent finding; however, marked elevation can also occur.
Malaria should be always suspected in every returning traveller who is febrile; however, with the presence of rash, arthralgia, leukopenia, thrombocytopenia and the absence of anemia, dengue fever is a more likely diagnosis. A returned traveller with myalgia and fever <39°C is more likely to have dengue fever than malaria.
Leptospirosis is among differential diagnoses of dengue fever and should be thought of in appropriate setting. In Australia, leptospirosis is almost exclusively an occupational disease seen in farmland workers and meat industry workers. Leptospirosis follows contamination of abraded or cut skin or mucous membrane with Leptospira-infected urine of animals such as sheep, goat, pig, horse, rat and dog. Clinical manifestations include fevers, chills, myalgia, and headache and light- sensitive conjunctivitis. The absence of such contacts in history makes leptospirosis a remote possibility.

Sore throat and generalized lymphadenopathy are characteristic features of infectious mononucleosis, the absence of which make such diagnosis less likely. Furthermore, lymphocytosis is a characteristic finding in infectious mononucleosis. This patient has leukopenia, not leukocytosis. This makes infectious mononucleosis a less likely diagnosis.

Question 31

A 45-year-old man, who has recently migrated to Australia, presents with recent history of productive cough and yellow sputum that is sometimes associated with streaks of blood. He has lost seven kg in the past three months. He smokes 10 cigarettes a day. On examination, he has normal vital signs. There are few small painful nodules on his legs that are shown in the following photograph. The rest of the examination is inconclusive. Which one of the following could be the most likely diagnosis?

A. Bronchogenic carcinoma.
B. Pulmonary tuberculosis.
C. Sarcoidosis.
D. Pneumococcal pneumonia.
E. Atypical pneumonia.

Answer 31

B. Pulmonary TB

The clinical description of the nodules alongside their appearance in the photograph is highly suggestive of erythema nodosum (EN).
EN is an acute, nodular, erythematous eruption usually limited to the extensor aspects of the lower legs. EN assumed to be a hypersensitivity reaction and may occur in association with several systemic diseases or drug therapies, or it may be idiopathic. EN is seen in the following conditions:
1. Bacterial infections
-Streptococcal infection – one of the most common causes of EN
-Mycoplasma tuberculosis – TB should always be considered in developing countries Yersinia enterocolitica
-Mycoplasma pneumonia
-Salmonella infection
2. Fungal infection -Coccidioidomycosis
3. Drugs
-Sulfonamide and halide agents – important causes of drug-induced EN -Gold
-Sulfonylureas
-Oral contraceptive pills

4. Enteropathies – ulcerative colitis and Crohn disease can trigger EN. EN associated with enteropathies correlate with flares of the disease. The mean duration of chronic ulcerative colitis before the onset of erythema nodosum is five years. EN is the most frequent dermatologic symptom in inflammatory bowel disease (IBD), and it is strongly associated with Crohn disease.
5. Hodgkin disease and lymphoma
6. Sarcoidosis - the most common cutaneous manifestation of sarcoidosis
7. Behçet disease
8. Pregnancy

Pulmonary tuberculosis and sarcoidosis share so many characteristic features that they might be confused clinically. Both pulmonary TB and sarcoidosis present with weight loss, malaise, fever, cough and sputum as well as EN; however, hemoptysis (coughing up blood) is a rare and unusual finding yet not impossible finding in sarcoidosis. Therefore, pulmonary TB is more likely to be the diagnosis than sarcoidosis.
Streptococcal infections including pneumococcal pneumonia are very common causes of EN, but weight loss and chronicity of the symptoms make this diagnosis unlikely. Mycoplasma pneumonia causes atypical pneumonia and may be associated with EN, but again the weight loss makes it a less likely possibility.

Question 32

A 22-year-old man presents to your practice in Darwin (Northern Territory) with complaints of rash and malaise and fatigue for the past few weeks. He is originally from Asia but has been living in Darwin for the past 3 months as a backpacker. On examination, vital signs including temperature are within normal limits. He has a maculopapular rash over the soles and palms that are non-pruritic, and cervical, axillary, and inguinal lymphadenopathy which is not tender. There are also two small alopecic patches on his head. Which one of the following is the most appropriate treatment option for him?

A. Doxycycline.
B. Benzylpenicillin.
C. Azithromycin.
D. Procainepenicillin.
E. Intramuscular ceftriaxone.

Answer 32

B. Benzylpenicillin

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It is transmitted through sexual contact, from mother to fetus, via blood transfusion, or through direct contact with infectious lesions.

1. Primary Syphilis
   
   • Onset: 10-90 days after exposure.
   • Symptoms: Solitary, firm, red papules (chancres) on the genitals, anus, fingers, or other extragenital sites. These lesions can ulcerate and are often painless. They heal within 4-8 weeks, with or without treatment.
   • Lymphadenopathy: Non-tender regional lymph nodes.
2. Secondary Syphilis
   
   • Symptoms: Rash, mucous membrane lesions, and lymphadenopathy. The rash can involve the palms and soles.
   • Systemic Involvement: Fever, sore throat, malaise, weight loss, and muscle aches.
   • Diagnosis: Clinical findings and serologic tests.
3. Latent Syphilis
   
   • Early Latent: The first year after primary or secondary syphilis. Asymptomatic but serologically positive.
   • Late Latent: More than a year after infection. Not infectious except for in utero transmission.
   • Detection: Only through serologic testing.
4. Tertiary Syphilis
   
   • Onset: Years after initial infection if untreated.
   • Symptoms: Can affect any organ. Includes gummatous lesions, cardiovascular syphilis, and neurosyphilis. Symptoms range from neurologic deficits and dementia to aortic aneurysms and deep bone pain.
   • Diagnosis: Based on clinical presentation and serologic tests.

• Diagnosis: Clinical evaluation, serologic testing (e.g., RPR, VDRL), and sometimes direct detection of Treponema pallidum.
• Standard Treatment:
  
  • Benzathine penicillin G: 2.4 million units IM as a single dose for primary, secondary, and early latent syphilis.
  • Procaine penicillin: 1.0 g IM daily for 10 days for tertiary syphilis.
  • Alternative for Penicillin-Allergic Patients: Doxycycline.

• Assessment: Evaluate sexual risk behaviors and provide education to prevent reinfection and transmission of other STIs.
• Follow-Up: Regular serologic testing to ensure treatment success and monitor for potential reinfection.

This simplified guide covers the key aspects of syphilis, its stages, diagnosis, treatment, and management. For more detailed information, consulting medical guidelines or a healthcare professional is recommended.

The scenario and the clinical findings are highly suggestive of secondary syphilis as the most likely diagnosis for which penicillin is the standard treatment.
Syphilis is a sexually transmissible infection caused by the spirochete . Syphilis is transmissible by sexual contact with infectious lesions, from mother to fetus in utero, via blood product transfusion, and occasionally through breaks in the skin that come into contact with infectious lesions. If untreated, it progresses through 4 stages: primary, secondary, latent, and tertiary.

Primary syphilis
Primary syphilis occurs 10-90 days after contact with an infected case, and mainly manifests on the glans penis in males and on the vulva or cervix in females. Almost 10% of syphilitic lesions are found on the anus, fingers, oropharynx, tongue, nipples, or other extragenital sites. Regional nontender lymphadenopathy follows invasion.
Lesions (chancres) usually begin as solitary, raised, firm, red papules that can be as large as several centimeters in diameter. The chancre erodes to create an ulcerative crater within the papule, with slightly elevated edges around the central ulcer. It usually heals within 4-8 weeks, with or without therapy. The lesions may be small and be overlooked or unnoticed by the patients.

Secondary syphlis
The scenario and the clinical findings are highly suggestive of secondary syphilis as the most likely diagnosis for which penicillin is the standard treatment.
Syphilis is a sexually transmissible infection caused by the spirochete . Syphilis is transmissible by sexual contact with infectious lesions, from mother to fetus in utero, via blood product transfusion, and occasionally through breaks in the skin that come into contact with infectious lesions. If untreated, it progresses through 4 stages: primary, secondary, latent, and tertiary.
Primary syphilis
Primary syphilis occurs 10-90 days after contact with an infected case, and mainly manifests on the glans penis in males and on the vulva or cervix in females. Almost 10% of syphilitic lesions are found on the anus, fingers, oropharynx, tongue, nipples, or other extragenital sites. Regional nontender lymphadenopathy follows invasion.
Lesions (chancres) usually begin as solitary, raised, firm, red papules that can be as large as several centimeters in diameter. The chancre erodes to create an ulcerative crater within the papule, with slightly elevated edges around the central ulcer. It usually heals within 4-8 weeks, with or without therapy. The lesions may be small and be overlooked or unnoticed by the patients.

Latent syphilis
Latency may last from a few years to as many as 25 years before the destructive lesions of tertiary syphilis manifest. Affected patients may recall symptoms of primary and secondary syphilis. They are asymptomatic during the latent phase, and the disease is detected only by serologic tests.
Latent syphilis is divided into early latent and late latent. The distinction is important because treatment for each is different. The early latent period is the first year after the resolution of primary or secondary syphilis. Asymptomatic patients who have a newly active serologic test after having a serologically negative test result within 1 year are also considered to be in the early latent period. Late latency syphilis is not infectious; however, women in this stage can spread the disease in utero.

Tertiary syphilis
Tertiary (late) syphilis is slowly progressive and may affect any organ. The disease is generally not thought to be infectious at this stage. Manifestations may include the following:
Impaired balance, paresthesias, incontinence, and impotence
Focal neurologic findings, including sensorineural hearing and vision loss Dementia
Chest pain, back pain, stridor, or other symptoms related to aortic aneurysms
The lesions of gummatous tertiary syphilis usually develop within 3-10 years of infection. The patient complaints are usually secondary to bone pain, which is described as a deep boring pain characteristically worse at night. Trauma may predispose a specific site to gumma involvement.
CNS involvement may occur, with presenting symptoms representative of the area affected. Patients with brain involvement may present with headache, dizziness, mood disturbance, neck stiffness, or blurred vision while spinal cord involvement can present with bulbar symptoms, weakness and wasting of shoulder girdle and arm muscles, incontinence, and impotence.
Some patients may present up to 20 years after infection with behavioral changes and other signs of dementia, which is indicative of paresis. Treatment of syphilis is by intramuscular injection using procaine penicillin or benzathine penicillin:
Benzathine penicillin 1.8 g (2.4 mU) IM as a single dose Procaine penicillin 1.0 g IM daily for 10 days
The best option to consider in this patient is benzathine penicillin because procaine penicillin must be given as a daily injection for 10 days, which can be uncomfortable and inconvenient for the patient. Doxycycline is the alternative for non-pregnant patients with allergy to penicillin.
Management of the infected individual should include an assessment of sexual risk and provision of information and support to reduce risks for re-infection or acquisition of other STIs

*** READ PAGE 691-695 (a lot of pictures and better organisation)

Question 33

A 35-year-old man, who is a know case of HIV infection, presents to the Emergency Department with complaints of fever, cough, and sputum for the past 48 hours. On examination, he has a blood pressure of 110/67 mmHg, PR of 110 bpm, temperature of 39.1°C, and respiratory rate of 32 breaths per minute. Chest exam is remarkable for dullness below the right scapula. A chest X-ray confirms a consolidation in the lower lobe of the right lung. In blood tests, white cell count of 14,000, ESR of 30, CRP of 21 mg/d and CD4 count of 55/mm3 are of significance. Which one of the following could be the most likely diagnosis?

A. Pneumocystis jiroveci pneumonia.
B. Mycoplasma pneumonia.
C. Staphylococcal pneumonia.
D. Streptococcal pneumonia.
E. Viral pneumonia.

Answer 33

D. Streptococcal pneumonia

1. Streptococcus pneumoniae
- Common Cause: Most frequent cause of bacterial pneumonia in both the general population and immunocompromised individuals (e.g., HIV patients).
- Symptoms: High-grade fever, productive cough, chest pain, and difficulty breathing.
- Diagnosis: Based on clinical presentation and chest X-ray findings.

2. Pneumocystis jiroveci Pneumonia (PJP)
- Cause: A fungus, Pneumocystis jiroveci, commonly seen in late-stage HIV infection or in those not adhering to PJP prophylaxis.
- Symptoms: Subacute onset with fever, dry cough, chest tightness, dyspnea, and fatigue. Symptoms may persist for weeks.
- Diagnosis: Suspected in patients with CD4+ T cell count <200/μL and lack of prophylaxis. Tachypnea, oxygen desaturation on exertion, and crackles may be noted.
- Risk Factors: Immunodeficiency, particularly with low CD4+ counts and poor HIV control.

3. Mycoplasma pneumoniae
- Common in CAP: Up to 40% of community-acquired pneumonia (CAP) cases.
- Symptoms: Gradual onset with low-grade fever, malaise, and persistent cough that may be non-productive or mildly productive.
- Diagnosis: Less likely if the patient presents with rapid-onset high fever and productive cough.

4. Staphylococcus aureus
- Rapid Course: Associated with fever and productive cough, often resistant to antibiotics.
- Common in Hospitalized Patients: More frequent in hospitalized or immunocompromised individuals rather than typical CAP.
- Symptoms: Severe respiratory symptoms and poor response to standard antibiotic therapy.

5. Viral Pneumonia
- Preceding Symptoms: Often follows flu-like symptoms (e.g., fever, cough, muscle aches).
- Diagnosis: Typically shows bilateral patchy infiltrates on chest X-ray, which differs from bacterial pneumonia findings.

• Streptococcus pneumoniae: Most common cause of bacterial pneumonia; high fever, productive cough.
• Pneumocystis jiroveci Pneumonia (PJP): Common in late-stage HIV; dry cough, chest tightness, fatigue, often with low CD4 counts.
• Mycoplasma pneumoniae: Gradual onset; low fever, persistent cough.
• Staphylococcus aureus: Rapid onset; high fever, productive cough; common in hospitalized/immunocompromised patients.
• Viral Pneumonia: Often follows flu-like symptoms; different chest X-ray findings.

This guide simplifies the identification and understanding of different pneumonia causes based on their typical presentations and patient history.

Streptococcus pneumoniae is the most common cause of bacterial pneumonia both in general population and individuals with compromised immunity such as HIV infected patients.
Pneumocystis jiroveci (P. jiroveci) (formerly known as pneumocystis carinii) is a ubiquitous fungus. By far, P.jiroveci pneumonia (PJP) is the most common AIDS-defining condition and usually is seen in HIV- infected individuals late in the course of HIV infection, or those who have poor adherence to PJP prophylaxis.
PJP presents sub-acutely with fever, non-productive (dry) cough, chest tightness, dyspnea, and tiredness. Symptoms may be present for 2 to 6 weeks or even more before a certain diagnosis of JPJ is made. Patients typically are immunodeficient (CD4+ T cell count < 200/μL), with failed suppression of HIV replication, and not taking cotrimoxazole prophylaxis, who present with fatigue and fever. Respiratory examination is often unremarkable except for probable tachypnea and oxygen desaturation on exertion. Crackles may be present on auscultation.
Mycoplasma pneumonia comprises up to 40% of CAPs. It has a gradual and insidious onset of several days to weeks. The patient’s history may include the following:
-Fever, generally low-grade
-Malaise
-Persistent, slowly worsening, incessant cough. The cough ranges from non-productive to mildly productive with sputum discoloration developing late in the course of the illness. The absence of cough makes the diagnosis of mycoplasma pneumonia unlikely.

The clinical picture of rapid-onset symptoms of high-grade fever and productive cough and the absence of the other features of mycoplasma pneumonia make such diagnosis less likely.
Pneumonia caused by staphylococcus aureus has a rapid course with fever, and productive cough, which often does not satisfactorily respond to antibiotic therapy.
Staphylococcal pneumonia is less likely of a diagnosis in community acquired pneumonia (CAP) and is more likely to occur in hospitalized or immunocompromised individuals.
Viral pneumonia is usually preceded by flu-like symptoms which are absent in this patient’s history. Moreover, CXR findings in viral pneumonia are typically bilateral patchy infiltrates which is different from CXR findings of this patient.

Question 34

Melany, 75 years old, was admitted to the hospital 5 days ago after she was diagnosed with bacterial community acquired pneumonia. She was started on intravenous antibiotics with a desirable therapeutic response and feeling much better. on her 5th day admission, she suddenly develops a high fever of 39.5°C, chills, and rigors. Which one of the following could be the most likely explanation to this clinical picture?

A. Hospital acquired pneumonia.
B. Lung abscess.
C. IV cannula-related bacteremia.
D. Empyema.
E. Pulmonary embolism.

Answer 34

C. IV cannula-related bacteremia

Melany develops high grade fever, chills, and rigors after recovering from her pneumonia owing to a favorable response to intravenous antibiotics. IV cannula- associated bacteremia and sepsis is the most common cause of bloodstream infections in hospitalized patients in Australia.
Empyema and lung also can also complicate pneumonia. However, the expected clinical course of empyema and lung abscess in Melany would have been poor or no response to initial antibiotics followed by the worsening of existing or addition of new symptoms. Melany had a favorable response to antibiotic therapy and was feeling well before new symptoms develop. This makes lung abscess and empyema less likely. Moreover, these conditions tend to develop insidiously rather than suddenly.
Hospital acquired pneumonia (HAP) is defined as pneumonia occuring 48 hours or more after hospital admission and not incubating at the admission time. Timeline-wise, HAP could also be a possibility for Melany; however, it the case was pneumonia, worsening of previous symptoms or build-up of new would be expected which is not mentioned in the scenario. On the other hand and from commonality point of view, IV cannula-associated bacteremia is a more likely possibility compared to HAP.

Acute pulmonary embolism presents with sudden onset pleuritic chest pain and shortness of breath. It is unusual for pulmonary embolism to present with high fever, chills, and rigor.

Question 35

A 12-year-old boy is brought to your clinic with complaint of an eyelid swelling that developed one week ago. The lesion is illustrated in the following photograph. The child is otherwise healthy. Which one of the following would be the most likely diagnosis?

A. Stye.
B. Blepharitis.
C. Carbuncle.
D. Chalazion.
E. Periorbital cellulitis.

red lump on upper eyelid

Answer 35

D. Chalazion

The photograph shows a swelling of the right upper eyelid. At the first look, it appears to be either hordeolum (stye) or chalazion (infection of a meibomian gland). With the lesion being distal to the eyelid, chalazion would be more likely because stye tends to be located more marginally. With resolution of acute infection, the abscess gives rise to nodule formation, namely meibomian cyst. It is not inflamed but may be locally irritating.
Stye is, in fact, the carbuncle of eyelash where the eyelash follicle becomes obstructed and infected. Stye is located more marginally and has inflammatory features.
Blepharitis presents with inflamed margins of the eyelids. It may be caused by Staph aureus, seborrheic dermatitis, or rosacea. It presents with marginal itching and burning. The management is with removal of crusts from the lids and steroid drops or creams. For blepharitis associated with staph aureus, tetracycline or chloramphenicol ointments are used. Oral doxycycline in indicated in those with blepharitis associated with rosacea.

Carbuncle of the eyelash (stye) presents at the margin of the eyelid.
Periorbital cellulitis presents differently with warmth, erythema and swelling around the orbit and often systemic upset. Absence of such findings makes this diagnosis unlikely.

Question 36

Which one of the following is caused by the inflammation of meibomian glands?

A. External hordeolum (stye).
B. Internal hordeolum (meibomian abscess).
C. Pinguecula.
D. Pterygium.
E. Blepharitis.

Answer 36

B. Internal hordeolum (meibomian abscess)

Obstruction, infection (usually by Staphylococcus aureus) and the residual nodule in the meibomian gland is referred to as chalazion also called meibomian cyst or internal hordeolum.

(Option A) External hordeolum (stye) is the infection of a lash follicle. It is usually self-limiting. Application of heat and plucking the affected lash are of much help. Topical antibiotics (e.g. chloramphenicol) may be used especially if the surrounding tissue is inflamed as well.

(Options C and D) Pinguecula is a benign growth of the conjunctiva. The structure is slightly raised, vascular and usually yellow grey. It can be on either side of the cornea, but it is more common on the nasal side. When the growth extends to cover the cornea, it is referred to as pterygium. Pterygium (surfer’s eye) is more common in those exposed to dust and wind blow. Pinguecula often does not require treatment except for cosmetic issues. If it becomes inflamed a short course of topical corticosteroids is advised. Keeping the eye moist and wearning sunglasses prevents inflammation. With progression to pterygium, removal is indicated.

(Option E) Blepharitis is inflammation of the lids caused by Staphylococcus aureus infection, seborrheic dermatitis, or rosacea. It presents with marginal eyelid itching and burning. Management is with removal of crusts from the lids and steroid drops or creams. For blepharitis associated with Staphylococcus aureus, tetracycline or chloramphenicol ointments is used. Oral doxycycline is indicated in those with blepharitis associated with rosacea.

References * Therapeutic Guidelines – Antibiotics; available from http://tg.org.au * http://emedicine.medscape.com/article/1212709-over

Question 37

A 30-year-old woman, who is 34 weeks pregnant, presents with dysuria and frequency. On examination, she has a temperature of 37.3°C. There is no nausea and vomiting, flank pain or tenderness A urine dipstick test is positive for nitrites and leucocytes. A mid-stream urine sample is sent for culture and sensitivity. In the meanwhile, which one of the following antibiotics is the medication of choice for empiric therapy in this woman?
A. Cephalexin.
B. Trimethoprim plus folic acid supplementation.
C. Doxycycline.
D. Nitrofurantoin.
E. Ciprofloxacin.

Answer 37

A. Cephalexin

The clinical manifestation is characteristic of urinary tract infection (UTI). With absence of fever and flank pain, infectious cystitis is more likely.

During pregnancy the following antibiotics are considered safe for treatment of UTI:
- First line Cephalexin (category A) 500mg orally, 6-hourly for 10 days
- Second line Nitrofurantoin (category A) 50mg orally, 6-hourly for 10 days
- Third line Amoxycillin + clavulanate (category B1) 500+125mg orally, 12-hourly for 10 days The above drugs are used for treatment of asymptomatic bacteriuria of pregnancy as well.

(Option B) Trimethoprim is an antagonist of folate and there might be increased potential risk of neural tube defects. Manufacturers advise that this drug be avoided during pregnancy. This drug, however, is the first-line therapy for UTI in non- pregnant women and adult men.

(Option C) Tetracyclines such as doxycyclin and tetracyclin are contraindicated in pregnancy due to their risk of teratogenicity.

(Option D) Nitrofurantoin is inferior ro cephalexin for treatment of UTI during pregnancy. Moreove, it should be avoided near term due to risk of neonatal hemolysis. It also should be avoided in those with renal impairment because the drug has renal excretion.

(Option E) Ciprofloxacin is a fluoroquinolone. Although fluoroquinolones are categorized as B1 and are almost safe for use during pregnancy, they should not be considered as first-line medications because they are the only orally-active drugs available for infections due to Pseudomonas aeruginosa and other resistant bacteria to conventional antibiotics.

Question 38

A 75-year-old man presents to your clinic with cough and rusty-colored sputum for 2 days. On examination, he has a blood pressure of 110/85 mmHg, pulse of 125bpm, respiratory rate of 32 breaths per minute and temperature of 38.6°C. Chest X-ray (CXR) shows consolidation in the right middle and lower lobes. Which one of the following is the most appropriate management?

A. Amoxicillin/clavulanate.
B. Ampicillin.
C. Erythromycin.
D. Intravenous penicillin.
E. Intravenous ceftriaxone.

Answer 38

D. Intravenous penicillin

The clinical and CXR findings of this patient are highly suggestive of community acquired pneumonia (CAP).

There are several ways to stratify the risk index for patients with CAP such as CURB-65, SMARTACOP, and Pneumonia Severity Index (PSI).

Pneumonia Severity Index (PSI) PSI is a validated risk stratification instrument that can help in identifying patients with CAP who can safely be treated with outpatient antibiotics. A point value is given to a variety of clinical and laboratory parameters.

According to the score, every patient is placed into any of the five risk classes namely I, II, III, IV, and V.

PICTURE IN PG 643 (TABLE)

The first in management of a patient with CAP is to quickly assess whether the patient is in class I or other classes. The patient is in class I if: (see photo below)

in presence of even one of the above risk factors, laboratory tests including full blood count, serum electrolytes and creatinine, ABG (or VBG) analysis should be conducted to calculate the PSI and plan further management.

All patients with PaO2<60mmHg or oxygen saturation <94% should be admitted regardless of their PSI class

PICTURE IN PG 644
antibiotics table in pg 644

This patient is 75 years old (+75 scores), is male (+10) and has a pulse rate of 125 mmHg (10+). Based on PSI, he has a total score of 95, and is calssified as class IV with a 30-day mortality risk of 9.1%. For him, the antibiotics of choice isbenzyl penicillin. If the patient is penicillin allergic (rash, but not anaphylactic shock), intravenous ceftriaxone is considered.

TOPIC REVIEW
SMARTACOP is another validated assessment tool for pneumonoa severity. SMARTACOP score is calculated based on the presence of different clinical, laboratory and CXR findings.

table of smartacop can be found in pg 644/ you can google it

References * Therapeutic Guidelines – Antibiotic; available from http://tg.org.au * https://www.mja.com.au/journal/2010/192/3/pneumoni

Question 39

A 60-year-old man presents to the emergency department with a 3-day history of increased sputum production, fever and progressive shortness of breath. He has had productive cough with greenish sputum for the past 3 years. He explains that he coughs up of a cupful of green sputum every morning. A chest X-ray is obtained showing consolidation of the right lower lobe. Which one of the following would be the most appropriate treatment option?

A. Doxycycline.
B. Roxithromycin.
C. Ticarcillin-clavulanate.
D. Amoxicillin-clavulanate.
E. Azithromycin.

Answer 39

C. Ticarcillin-clavulanate

The current clinical presentation, as well as consolidation of the right lower lobe is suggestive of lobar pneumonia.

The 3-year history of the chronic cough and copious amount of purulent sputum indicates that this patient has bronchiectasis as well.

Bronchiectasis is permanent dilation of the bronchi and bronchiols characterized by recurrent or persistent bronchial infection and cough. Patients with bronchiectasis often have chronically purulent sputum. Sputum cultures in such patients may reveal organisms such as Hemophilus influenza, Streptococcus pneumoniae, Staphylococcus aureus, Branhamella catarrhalis, and Pseudomonas aeruginosa.

The presence of Pseudomonas aeruginosa in the airways of these patients is generally associated with more severe disease. Colonization of the airway with these organisms is an indication for antibiotic treatment.

Exacerbations of bronchiectasis empirically treated with amoxicillin. Ciprofloxacin is used if the causative organism is found to be Pseudomonas aeruginosa. Every patient with pneumonia and an underlying lung pathology, such as cystic fibrosis or bronchiectasis, that makes Pseudomonas aeruginosa a likely causative organism should be initially treated with either of the following antibiotic regimens: - - Ticarcillin + clavulanate
- Piperacillin + tazobactam
- Cefotaxime
- Ceftriaxone
- Gentamicin

Any patient with history of chronic bronchiectasis who develops pneumonia should be admitted to the hospital for intravenous antibiotics. Macrolides such as roxithromycin or azithromycin do not cover Hemophilus influenza and are not options for treatment of infectious exacerbation of bronchiectasis.

Amoxicillin clavulanate or amoxicillin can be used for exacerbations of bronchiectasis where pneumonia is not a concern.

• Therapeutic Guidelines – Respiratory; available from http://tg.org.au * Therapeutic Guidelines – Antibiotic; available from http://tg.org.au

Question 40

As part of a health check, an immigrant Sudanese woman is found to have a positive tuberculin skin test (TST). A chest X-ray is obtained with inconclusive results. Sputum microscopy and culture are positive for tuberculosis (TB). She is planned to be started on four-drug therapy. She has a 4-year-old son and you make arrangements for him to have an interferon gamma release assay (IGRA) which turns out positive. The child is healthy and has no symptoms. Which one of the following would be the next best step in management?
A. No further action is required.
B. Start him on isoniazid.
C. Repeat the IGRA for the child.
D. Start him on 4-drug regimen.
E. Obtain a chest X-ray.

Answer 40

E. Obtain a chest X-ray.

This child is has been exposed to active TB infection and has a positive IGRA, but is asymptomatic. By definition, this child has latent tuberculosis infection (LTBI). LTBI means the patient has been infected with Mycobacterium tuberculosis (MTB), but does not have active tuberculosis. Unlike patients with active TB, those with LTBI cannot transmit the MTB to others. Generally, for patients with LTBI, there is a 10% lifetime risk of developing active TB ( 5% in the first 2 years after infection and 0.1% per year thereafter).

To diagnose the latent TB, 2 tests can be used:
- Tuberculin skin test (TST), also known as Mantoux test
- Interferon gamma release assays (IGRA)

NOTE - Australia’s National Tuberculosis Advisory Committee suggests TST as the preferred method of testing, with IGRA as a supplemental assay in patients older than 2 years. IGRA is easier to interpret in patients who are vaccinated with BCG or are immunocompromised.

TST (Mantoux) includes assessment of the skin inflammation 48-72 hours after intradermal (not subcutaneous) injection of 0.1ml of tuberculin protein (purified protein derivative or PPD). The diameter of the induration (not the erythema) measured across the arm (not along it) gives a semi-quantative assessment of the likelihood of LTBI.

TST is considered positive if the induration is ≥5mm in the following groups:
- Recent high risk (close) contacts of persons with infectious TB
- Indivuduals with organ transplants or immune suppressive therapy equivalent to prednisone >15mg/day for >1 month
- Individuals with HIV infection
- Individuals with CXR evidence of past untreated TB

TST is considered positive if the induration is ≥10 mm in the following groups:
- Individulas born or resident (for greater than 3 months) in countries with high prevalence of TB (>100 cases/100,000)
- Children < 4 years of age without any identified risk factors
- Individuals who live or spend time in high risk congregate settings (e.g. prisons, homeless shelters, alcohol rehabilitation and drug treatment centers
- Health care workers without prior BCG vaccination in the past 10 years
- Intravenous drug users

TST is considered positive if the induration is ≥15 mm in the following groups:
- Normal population other than the mentioned groups.

Factors that influence interpretation of TST are listed in the following:
Factors that may DECREASE skin reaction and give false-negative results
1. Infections: Viral e.g. HIV, measles, mumps, chickenpox, etc; Bacterial e.g. pertussis, brucellosis, leprosy, etc; Fungal Live virus vaccination e.g. measles, mumps, polio, etc
2. Metabolic diseases e.g. chronic renal failure
3. Malnutrition/ protein depletion
4. Lymphoid neoplasms e.g. Hodgkin’s disease, lymphoma, CML
5. Sarcoidosis
6. Drugs e.g. corticosteroids, immunosuppressants
7. Age – newborn and elderly
8. TB infection acquired within the past 8 weeks
9. Other causes leading to cell-mediated immune response suppression
10. Local skin damage e.g. trauma, dermatitis, surgery
11. Incorrect storage and handling of tuberculin (PPD)
12. Poor technique of injection and misreading

Factors that may INCREASE skin reaction and give false-positive results:
1. Exposure to or infection with non-tuberculosis mycobacteria
2. Past BCG vaccination
3. Trauma and irritation to the site of injection prior to reading
4. Misreading

Interferon Gamma Release Assay (IGRA) is unaffected by previous BCG vaccination. A positive IGRA suggests that the patient’s immune system recognizes MTB antigens due to either current infection or a past infection. A negative test cannot exclude active TB because sensitivity is not 100%

NOTE - TST remains the preferred method with IGRAs as a supplemental assay in subjects more than 2 years of age. TST alone is recommended for those ≤2 years of age.

If a TST or IGRA is positive, active disease must be excluded with chest X-ray as the next best step in management.

If the chest X-ray is normal, active TB is excluded and the patient should only be treated for LTBI with INH (and pyridoxine) for 6-9 months.

If the chest X-ray shows abnormalities, sputum should be examined for acid-fast bacilli (AFB) stain and culture. An abnormal chest X-ray and 3 negative sputum smears excludes active TB, and the patient should only be treated for LTBI with INH (300mg/day) and pyridoxine for 6-9 months.

With even one positive sputum exam, the patient is considered to have active TB and is treated with standard full-dose 4-drug therapy after discussion with and supervision of a clinician experienced in TB management

References * RACGP - Tuberculosis testing * Australian Prescriber - Testing for tuberculosis * Therapeutic Guidelines – Antibiotics: available from http://tg.org.au

Question 41

On a routine health evaluation for immigration, a 45-year-old Asian man is found to have a positive tuberculin skin test (TST). He denies cough, fever, sputum, or weight loss. A complete physical examination is normal. A chest X-ray is obtained that is shown in the following photograph. Which one of the following is the next best step in management of this patient?

A. Start him on quadruple therapy for active TB.
B. Start him on monotherapy with isoniazid for 9 months.
C. Obtain sputum sample for acid fast bacilli (AFB) stain and culture.
D. Repeat the chest X-ray in 6 months.
E. Repeat the TST in 2 weeks.

Answer 41

C. Obtain sputum sample for acid fast bacilli (AFB) stain and culture.

Latent tuberculosis infection (LTBI) means the patient has been infected with Mycobacterium Tuberculosis (MTB), but does not have active tuberculosis. Unlike patients with active TB, those with LTBI cannot transmit the MTB to others. Generally, for patients with LTBI there is a 10% lifetime risk of developing active TB ( 5% in the first 2 years after infection and 0.1% per year thereafter).

To diagnose the latent TB, 2 tests can be used:
1. Tuberculin skin test (TST), also known as Mantoux test
2. Interferon gamma release assays (IGRA)

NOTE - Australia’s National Tuberculosis Advisory Committee suggests TST as the preferred method of testing, with IGRA as a supplemental assay in patients older than 2 years. IGRA is easier to interpret in patients who are vaccinated with BCG or are immunocompromised.

A positive TST or IGRA indicates that the patient has either active or latent Mycoplasma tuberculosis (MTB) infection. In such cases, the next best step in management is obtaining a chest X-ray.

If the chest X-ray is normal, active TB is excluded and the patient should only be treated for LTBI with INH (and pyridoxine) for 6-9 months.

If the chest X-ray shows abnormalities, sputum should be examined for acid-fast bacilli (AFB) stain and culture. An abnormal chest X-ray and 3 negative sputum smears excludes active TB, and the patient should only be treated for LTBI with INH (300mg/day) and pyridoxine for 6-9 months.

However, with even one positive sputum exam, the patient should be thought as having active TB and started on the standard full-dose four-drug therapy after discussion with and supervision of a clinician experienced in TB management.

This patient has a positive TST. Furthermore, his chest X-ray shows opacities in the apex of the right lung, consistent with TB infection. With the abnormal chest X-ray, the next best step would be obtaining three samples for acid FAST stain and culture.

(Option A) Starting the patient on four-drug therapy is the correct option if the patient has active TB. Unless there is at least one positive sputum sample for TB, the provisional diagnosis is LTBI and not active TB infection; therefore, quadruple therapy is not necessary.

(Option B) Although monotherapy with isoniazid for 6-9 months is used for treatment of LTBI, this patient might have active TB infection. The decision as to whether this patient should be treated for active or latent TB cannot be made until sputum exam results are available.

(Option D) Repeating the chest X-ray in 6 months is not appropriate because this patient has a positive TST result and chest X-ray findings consistent with current or previous TB infection. Action should be taken for further assessment and prompt treatment of LTBI or active TB based on assssment results. Repeating the chest X-ray adds no benefit and unnecessarily delays treatment.

(Option E) A TST should never be repeated once it is positive.

References * RACGP - Tuberculosis testing * Australian Prescriber - Testing for tuberculosis * Therapeutic Guidelines – Antibiotics: available on: http://tg.org.au

Question 42

A 47-year-old woman presents to your practice with complaints of fever, cough and hemoptysis. She is a nurse working in a rural area and has smoked 15 cigarettes a day for the past 20 years. She also has lost eight kg in the past three months. Her physical examination is unremarkable. A chest X-ray is obtained and shown in the following photograph. Which one of the following is the most appropriate next step in management?

A. Obtain sputum sample for Gram stain.
B. Bronchoscopy and lavage.
C. Obtain sputum sample for Zihel - Neelsen stain.
D. High-resolution CT scan of the chest.
E. Start the patient on full-dose four-drug therapy for tuberculosis.

Answer 42

C. Obtain sputum sample for Zihel - Neelsen stain.

Clinical findings of fever, cough, hemoptysis, and weight loss, in the presence of a lesion seen in the upper lobe of the right lung is highly suggestive of pulmonary tuberculosis (TB). This patient should be considered to have TB unless proven otherwise. When TB is suspected, the next step will be obtaining three sputum samples for acid-fast (Zihel-Neelsen) bacilli staining and culture.

(Option A) Gram-stain does not show TB bacilli and is not used for diagnosing TB.

(Option B) Bronchoscopy and lavage for obtaining samples are indicated if traditionally-obtained samples are negative but, based on clinical grounds, TB is a likely diagnosis.

(Option D) High resolution CT scan of the chest has no role in diagnosis of TB and is not indicated unless the diagnosis is not certain or other diagnoses than TB are considered..

(Option E) Starting the patient on full-dose 4-drug therapy for tuberculosis is indicated in this patient due to high possibility of TB as the diagnosis, but it should be delayed until samples are taken because antibiotics, if used prior to testing, may alter test results, mostly in form of false negativity.

References * RACGP - Tuberculosis testing * Australian Prescriber - Testing for tuberculosis * Therapeutic Guidelines – Antibiotics: available from http://tg.org.au

Question 43

Melany, 75 years old, was admitted to the hospital 5 days ago after she was diagnosed with bacterial community acquired pneumonia. She was started on intravenous antibiotics with a desirable therapeutic response and feeling much better. on her 5th day admission, she suddenly develops a high fever of 39.5°C, chills, and rigors. Which one of the following could be the most likely explanation to this clinical picture?
A. Hospital acquired pneumonia.
B. Lung abscess.
C. IV cannula-related bacteremia.
D. Empyema.
E. Pulmonary embolism.

Answer 43

**C. IV cannula-related bacteremia. **

Melany develops high grade fever, chills, and rigors after recovering from her pneumonia owing to a favorable response to intravenous antibiotics. Her current symptoms and sudden nature of onset is well aligned with bacteremia.

IV cannula- associated bacteremia and sepsis is the most common cause of bloodstream infections in hospitalized patients in Australia.

Empyema and lung also can also complicate pneumonia. However, the expected clinical course of empyema and lung abscess in Melany would have been poor or no response to initial antibiotics followed by the worsening of existing or addition of new symptoms. Melany had a favorable response to antibiotic therapy and was feeling well before new symptoms develop. This makes lung abscess (option B) and empyema (option D) less likely. Moreover, these conditions tend to develop insidiously rather than suddenly.

Hospital acquired pneumonia (HAP) (option A) is defined as pneumonia occuring 48 hours or more after hospital admission and not incubating at the admission time. Timeline-wise, HAP could also be a possibility for Melany; however, it the case was pneumonia, worsening of previous symptoms or build-up of new would be expected which is not mentioned in the scenario.

On the other hand and from commonality point of view, IV cannula-associated bacteremia is a more likely possibility compared to HAP.

Acute pulmonary embolism (option E) presents with sudden onset pleuritic chest pain and shortness of breath. It is unusual for pulmonary embolism to present with high fever, chills, and rigor.

References * Australian Prescriber – Controlling intravascular catheter infections * Medscape- Management of Catheter-related Infection

Question 44

A 45-year-old man, who has recently migrated to Australia, presents with recent history of productive cough and yellow sputum that is sometimes associated with streaks of blood. He has lost seven kg in the past three months. He smokes 10 cigarettes a day. On examination, he has normal vital signs. There are few small painful nodules on his legs that are shown in the following photograph. The rest of the examination is inconclusive. Which one of the following could be the most likely diagnosis?

A. Bronchogenic carcinoma.
B. Pulmonary tuberculosis.
C. Sarcoidosis.
D. Pneumococcal pneumonia.
E. Atypical pneumonia.

Answer 44

**B. Pulmonary tuberculosis. **

Definition: EN is an acute, nodular, erythematous eruption, usually on the extensor aspects of the lower legs. It is considered a hypersensitivity reaction.

Common Associations:
1. Bacterial Infections:
- Streptococcal infection (most common)
- Tuberculosis (especially in developing countries)
- Yersinia enterocolitica, Mycoplasma pneumonia, Salmonella

2. Fungal Infections:
   
   • Coccidioidomycosis
3. Drugs:
   
   • Sulfonamides, halide agents, gold, sulfonylureas, oral contraceptive pills
4. Enteropathies:
   
   • Ulcerative colitis and Crohn’s disease
5. Malignancies:
   
   • Hodgkin disease and lymphoma
6. Other Conditions:
   
   • Sarcoidosis, Behçet disease, pregnancy

Differential Diagnosis:
- Pulmonary Tuberculosis (TB): More likely than sarcoidosis if hemoptysis is present, with similar symptoms such as weight loss, malaise, fever, cough, and EN.
- Streptococcal Infections: Common cause but less likely with weight loss and chronic symptoms.
- Mycoplasma Pneumonia: Causes atypical pneumonia and may be associated with EN, but weight loss makes it less likely.
- Bronchogenic Carcinoma: No established association with EN.

• Primary Symptoms: Nodular, red eruptions on lower legs.
• Additional Symptoms: Weight loss, malaise, fever, cough, possible hemoptysis.
• Associated Conditions: Often linked with infections, drug reactions, autoimmune diseases, malignancies, and pregnancy.

A 30-year-old woman presents with red, tender nodules on her lower legs, fatigue, and weight loss.

1. What is the most likely diagnosis?
   
   • A) Cellulitis
   • B) Erythema nodosum
   • C) Erythema multiforme
   • D) Vasculitis
   • E) Dermatitis
   Answer: B) Erythema nodosumExplanation: The presence of red, tender nodules on the lower legs with systemic symptoms like fatigue and weight loss is characteristic of EN.
   • Why not A): Cellulitis typically presents with localized infection, not nodules.
   • Why not C): Erythema multiforme presents with target lesions.
   • Why not D): Vasculitis usually involves purpura.
   • Why not E): Dermatitis typically involves inflammation and itching, not nodules.

A 25-year-old man with erythema nodosum is found to have a cough, fever, and weight loss.

2. What is the most likely underlying cause?
   
   • A) Sarcoidosis
   • B) Streptococcal infection
   • C) Mycoplasma pneumonia
   • D) Tuberculosis
   • E) Hodgkin disease
   Answer: D) TuberculosisExplanation: The combination of cough, fever, weight loss, and EN suggests tuberculosis, especially in developing countries.
   • Why not A): Sarcoidosis can present similarly but is less likely with weight loss.
   • Why not B): Streptococcal infection is common but less likely with weight loss.
   • Why not C): Mycoplasma pneumonia causes atypical pneumonia but weight loss makes it less likely.
   • Why not E): Hodgkin disease is possible but TB is more likely with these symptoms.

A 40-year-old woman presents with erythema nodosum after starting a new medication.

3. Which of the following drugs is most likely responsible?
   
   • A) NSAIDs
   • B) Sulfonamides
   • C) Beta-blockers
   • D) ACE inhibitors
   • E) Statins
   Answer: B) SulfonamidesExplanation: Sulfonamides are a common cause of drug-induced EN.
   • Why not A): NSAIDs are not typically associated with EN.
   • Why not C): Beta-blockers are not a common cause of EN.
   • Why not D): ACE inhibitors are not associated with EN.
   • Why not E): Statins are not commonly associated with EN.

A 35-year-old woman with Crohn’s disease presents with erythema nodosum.

4. What is the relationship between her EN and Crohn’s disease?
   
   • A) EN is unrelated to Crohn’s disease
   • B) EN indicates a new infection
   • C) EN correlates with Crohn’s disease flares
   • D) EN suggests remission of Crohn’s disease
   • E) EN is a sign of drug toxicity
   Answer: C) EN correlates with Crohn’s disease flaresExplanation: EN is the most frequent dermatologic symptom in inflammatory bowel disease and is strongly associated with flares of Crohn’s disease.
   • Why not A): EN is related to Crohn’s disease.
   • Why not B): EN is not an indicator of a new infection in this context.
   • Why not D): EN is associated with active disease, not remission.
   • Why not E): EN is not a sign of drug toxicity in this context.

A 28-year-old woman presents with suspected erythema nodosum and systemic symptoms.

5. What is the best single test to establish the diagnosis of erythema nodosum?
   
   • A) Skin biopsy
   • B) Blood cultures
   • C) Minor salivary gland biopsy
   • D) Chest X-ray
   • E) ESR and CRP levels
   Answer: A) Skin biopsyExplanation: A skin biopsy can confirm the diagnosis of EN by demonstrating characteristic histopathological findings.
   • Why not B): Blood cultures are not diagnostic for EN.
   • Why not C): Minor salivary gland biopsy is used for Sjögren syndrome.
   • Why not D): Chest X-ray is not diagnostic for EN.
   • Why not E): Elevated ESR and CRP indicate inflammation but are not diagnostic.

The clinical description of the nodules alongside their appearance in the photograph is highly suggestive of erythema nodosum (EN).

EN is an acute, nodular, erythematous eruption usually limited to the extensor aspects of the lower legs. Rarely, EN can be chronic or recurrent. EN assumed to be a hypersensitivity reaction and may occur in association with several systemic diseases or drug therapies, or it may be idiopathic. EN is seen in the following conditions:
1. Bacterial infections
- Streptococcal infection – one of the most common causes of EN
- Mycoplasma tuberculosis – TB should always be considered in developing countries
- Yersinia enterocolitica
- Mycoplasma pneumonia
- Salmonella infection
2. Fungal infections – Coccidioidomycosis
3. Drugs
- Sulfonamide and halide agents – important causes of drug-induced EN
- Gold
- Sulfonylureas
- Oral contraceptive pills
4. Enteropathies – ulcerative colitis and Crohn disease can trigger EN. EN associated with enteropathies correlate with flares of the disease. The mean duration of chronic ulcerative colitis before the onset of erythema nodosum is five years. EN is the most frequent dermatologic symptom in inflammatory bowel disease (IBD), and it is strongly associated with Crohn disease.
5. Hodgkin disease and lymphoma
6. Sarcoidosis - the most common cutaneous manifestation of sarcoidosis
7. Behçet disease
8. Pregnancy

Pulmonary tuberculosis and sarcoidosis share so many characteristic features that they might be confused clinically. Both pulmonary TB and sarcoidosis present with weight loss, malaise, fever, cough and sputum as well as EN; however, hemoptysis (coughing up blood) is a rare and unusual finding yet not impossible finding in sarcoidosis. Therefore, pulmonary TB is more likely to be the diagnosis than sarcoidosis (option C).

Streptococcal infections including pneumococcal pneumonia (option D) are very common causes of EN, but weight loss and chronicity of the symptoms make this diagnosis unlikely.

Mycoplasma pneumonia causes atypical pneumonia (option E) and may be associated with EN, but again the weight loss makes it a less likely possibility.

The association between bronchogenic carcinoma (option A) and EN has not yet been established.

References * Medscape - Erythema Nodosum * Medscape - Sarcoidosis

Question 45

A 35-year-old man, who is a know case of HIV infection, presents to the Emergency Department with complaints of fever, cough, and sputum for the past 48 hours. On examination, he has a blood pressure of 110/67 mmHg, PR of 110 bpm, temperature of 39.1°C, and respiratory rate of 32 breaths per minute. Chest exam is remarkable for dullness below the right scapula. A chest X-ray confirms a consolidation in the lower lobe of the right lung. In blood tests, white cell count of 14,000, ESR of 30, CRP of 21 mg/d and CD4 count of 55/mm3 are of significance. Which one of the following could be the most likely diagnosis?
A. Pneumocystis jiroveci pneumonia.
B. Mycoplasma pneumonia.
C. Staphylococcal pneumonia.
D. Streptococcal pneumonia.
E. Viral pneumonia.

Answer 45

**D. Streptococcal pneumonia. **

Scenario: Patient with acute onset of cough, sputum production, fever, and focal findings on physical exam and chest x-ray.

Most Likely Diagnosis: Bacterial pneumonia

Common Cause: Streptococcus pneumoniae (most common in both general population and HIV-infected individuals).

1. Pneumocystis jiroveci Pneumonia (PJP):
   
   • Presentation: Subacute with fever, non-productive cough, dyspnea, fatigue.
   • Common in: Advanced HIV (CD4 <200).
   • Symptoms Duration: 2-6 weeks.
   • Key Features: Dry cough, tachypnea, oxygen desaturation on exertion, crackles.
2. Mycoplasma Pneumonia:
   
   • Presentation: Gradual onset with low-grade fever, malaise, persistent cough.
   • Symptoms: Sore throat, headache, chills (no rigors), chest pain (rare), wheezing.
   • Cough: Non-productive to mildly productive.
   • Key Features: Absence of rapid-onset high-grade fever.
3. Staphylococcus Aureus Pneumonia:
   
   • Presentation: Rapid course with fever and productive cough.
   • Complications: Cavitation, abscess, empyema, pleural effusion.
   • Key Features: Less common in community-acquired pneumonia, more in hospitalized/immunocompromised.
4. Viral Pneumonia:
   
   • Presentation: Preceded by flu-like symptoms.
   • CXR Findings: Typically bilateral patchy infiltrates.
   • Key Features: Absence of flu-like symptoms in this patient.

A 55-year-old man presents with acute onset of cough, sputum, and fever. His chest x-ray shows a focal consolidation.

1. What is the most likely diagnosis?
   
   • A) Pneumocystis jiroveci pneumonia
   • B) Mycoplasma pneumonia
   • C) Staphylococcus aureus pneumonia
   • D) Streptococcus pneumoniae pneumonia
   • E) Viral pneumonia
   Answer: D) Streptococcus pneumoniae pneumoniaExplanation: The acute onset and focal consolidation are most consistent with bacterial pneumonia, with Streptococcus pneumoniae being the most common cause.
   • Why not A): PJP presents subacutely with a non-productive cough.
   • Why not B): Mycoplasma pneumonia has a gradual onset.
   • Why not C): Staphylococcus pneumonia is less common in community settings.
   • Why not E): Viral pneumonia usually has flu-like symptoms and bilateral infiltrates.

A 40-year-old HIV-positive man presents with a 3-week history of fever, dry cough, and fatigue. His CD4 count is 150/μL.

2. What is the most likely diagnosis?
   
   • A) Streptococcus pneumoniae pneumonia
   • B) Mycoplasma pneumonia
   • C) Pneumocystis jiroveci pneumonia
   • D) Staphylococcus aureus pneumonia
   • E) Viral pneumonia
   Answer: C) Pneumocystis jiroveci pneumoniaExplanation: The subacute presentation, dry cough, and low CD4 count are consistent with PJP, common in advanced HIV.
   • Why not A): Bacterial pneumonia presents acutely.
   • Why not B): Mycoplasma pneumonia has a more gradual onset.
   • Why not D): Staphylococcus pneumonia is less likely in a non-hospitalized patient.
   • Why not E): Viral pneumonia often has preceding flu-like symptoms.

A 30-year-old woman has had a persistent cough, low-grade fever, and malaise for the past two weeks. She also reports a sore throat and headache.

3. What is the most likely diagnosis?
   
   • A) Streptococcus pneumoniae pneumonia
   • B) Mycoplasma pneumonia
   • C) Pneumocystis jiroveci pneumonia
   • D) Staphylococcus aureus pneumonia
   • E) Viral pneumonia
   Answer: B) Mycoplasma pneumoniaExplanation: The gradual onset, persistent cough, low-grade fever, and sore throat are characteristic of Mycoplasma pneumonia, a common cause of atypical pneumonia.
   • Why not A): Streptococcus pneumoniae pneumonia typically presents acutely.
   • Why not C): PJP presents with a dry cough and is more common in immunocompromised patients.
   • Why not D): Staphylococcus pneumonia has a rapid course and is less common in community-acquired cases.
   • Why not E): Viral pneumonia often has preceding flu-like symptoms.

A 65-year-old man presents with fever, productive cough, and weight loss. Chest x-ray shows cavitation and pleural effusion.

4. What is the most likely cause?
   
   • A) Streptococcus pneumoniae
   • B) Mycoplasma pneumonia
   • C) Pneumocystis jiroveci
   • D) Staphylococcus aureus
   • E) Viral pneumonia
   Answer: D) Staphylococcus aureusExplanation: The presence of cavitation and pleural effusion are complications more commonly associated with Staphylococcus aureus pneumonia.
   • Why not A): Streptococcus pneumoniae typically does not cause cavitation.
   • Why not B): Mycoplasma pneumonia usually has a milder course.
   • Why not C): PJP does not typically present with cavitation.
   • Why not E): Viral pneumonia typically does not cause cavitation or effusion.

A 28-year-old woman presents with fever, chills, non-productive cough, and bilateral patchy infiltrates on chest x-ray.

5. What is the most likely diagnosis?
   
   • A) Streptococcus pneumoniae pneumonia
   • B) Mycoplasma pneumonia
   • C) Pneumocystis jiroveci pneumonia
   • D) Staphylococcus aureus pneumonia
   • E) Viral pneumonia
   Answer: E) Viral pneumoniaExplanation: Bilateral patchy infiltrates and flu-like symptoms are typical of viral pneumonia.
   • Why not A): Streptococcus pneumoniae pneumonia usually presents with focal consolidation.
   • Why not B): Mycoplasma pneumonia can present similarly but usually has a more gradual onset.
   • Why not C): PJP presents subacutely and often in immunocompromised patients.
   • Why not D): Staphylococcus aureus pneumonia typically presents with more severe complications like cavitation.

With cough, sputum, and fever developing acutely and focal findings on physical examination and chest x-ray (CXR), bacterial pneumonia is the most likely diagnosis. Streptococcus pneumoniae is the most common cause of bacterial pneumonia both in general population and individuals with compromised immunity such as HIV infected patients.

(Option A) Pneumocystis jiroveci (P. jiroveci) (formerly known as pneumocystis carinii) is a ubiquitous fungus. By far, P. jiroveci pneumonia (PJP) is the most common AIDS-defining condition and usually is seen in HIV- infected individuals late in the course of HIV infection, or those who have poor adherence to PJP prophylaxis. JPJ is uncommon in people with CD4 counts of over 200.

PJP presents sub-acutely with fever, non-productive (dry) cough, chest tightness, dyspnea, and tiredness. Symptoms may be present for 2 to 6 weeks or even more before a certain diagnosis of JPJ is made. Patients typically are immunodeficient (CD4+ T cell count < 200/μL), with failed suppression of HIV replication, and not taking cotrimoxazole prophylaxis, who present with fatigue and fever. The patient may not necessarily have noticed cough or dyspnea, yet a non-productive cough is commonly apparent during the clinical assessment. Respiratory examination is often unremarkable except for probable tachypnea and oxygen desaturation on exertion. Crackles may be present on auscultation.

(Option B) Mycoplasma pneumonia comprises up to 40% of CAPs. It has a gradual and insidious onset of several days to weeks. The patient’s history may include the following:
- Fever, generally low-grade
- Malaise
- Persistent, slowly worsening, incessant cough. The cough ranges from non-productive to mildly productive with sputum discoloration developing late in the course of the illness. The absence of cough makes the diagnosis of mycoplasma pneumonia unlikely.
- Headache
- Chills but not rigors
- Scratchy sore throat
- Sore chest and tracheal tenderness as results of the protracted cough
- Pleuritic chest pain (rare)
- Wheezing
- Dyspnea (uncommon)

The clinical picture of rapid-onset symptoms of high-grade fever and productive cough and the absence of the other features of mycoplasma pneumonia make such diagnosis less likely.

(Option C) Pneumonia caused by staphylococcus aureus has a rapid course with fever, and productive cough, which often does not satisfactorily respond to antibiotic therapy. Cavitation, abscess formation, empyema, and pleural effusion are more likely to develop and be present on assessment compared to streptococcal pneumonia. Staphylococcal pneumonia is a possibility in this patient as well, but streptococcal pneumonia remains more likely as it is more common.

NOTE - Staphylococcal pneumonia is less likely of a diagnosis in community acquired pneumonia (CAP) and is more likely to occur in hospitalized or immunocompromised individuals.

(Option E) Viral pneumonia is usually preceded by flu-like symptoms which are absent in this patient’s history. Moreover, CXR findings in viral pneumonia are typically bilateral patchy infiltrates which is different from CXR findings of this patient.

• ASHM – Infectious diseases and cancers caused by HIV-induced immunodeficiency: Bacteria pneumonia