LE1 - INFECTIOUS 2023

Question 1

The most common presentation of extrapulmonary TB in both HIV-seronegative individuals and HIV-infected patients is:

A. Tuberculous lymphadenitis
B. Genitourinary TB
C. Skeletal TB
D. Pleural TB

Answer 1

A. Tuberculous lymphadenitis
Rationale: Tuberculous lymphadenitis is the most frequent form of extrapulmonary tuberculosis, commonly affecting the cervical lymph nodes. It is prevalent in both HIV-seronegative and HIV-infected patients, where it may present with painless swelling of the lymph nodes.

Question 2

A 25-year-old male presents with a discrete non-tender mass with a fistulous tract draining caseous material. Diagnosis can be established by aspiration or excision biopsy. Which of the following statements is incorrect?

A. Associated pulmonary TB is present in less than 50% of cases
B. Less organized granulomas and often absence of granulomas is seen among HIV-infected patients
C. Bacterial loads are heavier in HIV-infected patients than among HIV-seronegative patients
D. Cultures are 100% positive and necessary to make a diagnosis

Answer 2

D. Cultures are 100% positive and necessary to make a diagnosis (only 70-80%)
Rationale: Cultures for Mycobacterium tuberculosis are not always 100% positive; they typically have a positivity rate of 70-80%. Hence, relying solely on culture for diagnosis might not be sufficient.

Question 3

The mechanism of effusion in pleural TB is:

A. None of the above
B. May result from contiguous spread from parenchymal disease
C. All of the above
D. Hypersensitivity response to mycobacterial antigens

Answer 3

C. All of the above
Rationale: The effusion in pleural TB may result from contiguous spread from parenchymal disease, a hypersensitivity response to mycobacterial antigens, and other mechanisms such as lymphatic obstruction or direct invasion.

Question 4

The effusion in pleural TB is:

A. Transudative
B. Both
C. None of the above
D. Exudative

Answer 4

D. Exudative
Rationale: Pleural effusion in tuberculosis is typically exudative, characterized by high protein content and often lymphocyte predominance.

Question 5

The characteristics of effusion in pleural TB are:

A. Protein is less than 50% of the serum level, normal low to high glucose level, pH ~6.5, and absence of WBC
B. Protein is less than 50% of the serum level, with moderate to high glucose level, pH ~7.3, and WBC 300-400/uL
C. Protein is more than 50% of the serum level, with a normal to low glucose level, pH ~7.3, and WBC 500-6000/uL
D. Protein is more than 50% of the serum level, with a normal to low glucose level, pH ~6.5, and WBC >20/uL

Answer 5

C. Protein is more than 50% of the serum level, with a normal to low glucose level, pH ~7.3, and WBC 500-6000/uL
Rationale: The effusion in pleural TB typically shows high protein levels (more than 50% of serum level), a normal to low glucose level, a pH around 7.3, and a white blood cell count between 500-6000/uL.

Question 6

A pulmonary TB patient’s x-ray shows hydropneumothorax with air-fluid levels. The pleural fluid is thick and purulent with large numbers of lymphocytes. The best management is:

A. Surgical drainage such as CTT insertion with anti-TB regimen
B. Do culture and sensitivity on the pleural fluid and taper the treatment based on the results
C. Anti-TB regimen is sufficient
D. Surgical removal of the pleura followed by anti-TB regimen

Answer 6

A. Surgical drainage such as CTT insertion with anti-TB regimen
Rationale: Surgical drainage, such as chest tube thoracostomy (CTT) insertion, combined with an anti-TB regimen, is the best approach to manage a thick and purulent pleural effusion with air-fluid levels.

Question 7

TB of the upper airways has similar features to carcinoma of the larynx. The major difference is:

A. TB of the upper airways and carcinoma of the larynx present with productive cough, hoarseness, dysphonia, and dysphagia
B. Carcinoma of the larynx is usually painless
C. TB affects only the larynx, pharynx, and epiglottis
D. TB of the upper airways may result in ulceration (both may result in ulceration as visualized through laryngoscopy)

Answer 7

B. Carcinoma of the larynx is usually painless

Rationale: According to the differential diagnosis information, carcinoma of the larynx may have similar features to TB of the upper airways but is typically painless. This key difference helps distinguish between the two conditions.

Question 8

A pulmonary TB patient complained of recurrent dysuria, nocturia, and flank pains. Urinalysis showed pyuria and hematuria. Which of the following should raise suspicion of genitourinary TB?

A. Both
B. None of the above
C. Culture-negative pyuria in acidic urine
D. Culture-negative pyuria in alkaline urine

Answer 8

C. Culture-negative pyuria in acidic urine
Rationale: Genitourinary TB often presents with culture-negative pyuria, especially in acidic urine, due to the difficulty of isolating Mycobacterium tuberculosis from urine samples.

Question 9

The organ most commonly affected in men with genitourinary TB is:

A. Prostate
B. Renal parenchyma
C. Ureters
D. Epididymis

Answer 9

D. Epididymis
Rationale: The epididymis is the most commonly affected organ in men with genitourinary TB, often leading to a condition called tuberculous epididymitis.

Question 10

The organs most commonly affected in women with genitourinary TB are:

A. Cervix and myometrium
B. Ovaries and fallopian tubes
C. Fallopian tubes and endometrium
D. Cervix and ovaries

Answer 10

C. Fallopian tubes and endometrium
Rationale: In women, the fallopian tubes and endometrium are the most commonly affected organs in genitourinary TB, leading to symptoms such as infertility and pelvic pain.

Question 11

Skeletal TB primarily affects weight-bearing joints. The most commonly affected joint in 40% of the cases is:
A. All of the above
B. Hips
C. Spine
D. Knees

Answer 11

C. Spine
Rationale: Skeletal tuberculosis most commonly affects the spine (Pott’s disease), which accounts for approximately 40% of cases. It typically involves the thoracic and lumbar vertebrae.

Question 12

A 30-year-old skeletal TB patient sought consultation due to numbness and weakness. An X-ray of the spine was requested. Which part of the spine is most commonly affected in adults with skeletal TB?
A. Upper thoracic spine
B. Lower lumbar spine and sacrum
C. Lower thoracic spine and upper lumbar spine
D. Cervical spine

Answer 12

C. Lower thoracic spine and upper lumbar spine
Rationale: The lower thoracic and upper lumbar spine are the most commonly affected regions in adults with spinal TB. These areas are prone to infection due to the vascular supply and weight-bearing stress.

Question 13

The mode of spread in gastrointestinal TB is:
A. Swallowing of sputum with direct seeding and hematogenous spread
B. None of the above
C. All of the above
D. Ingestion of milk from affected cows with bovine TB

Answer 13

C. all of the above

Rationale: Gastrointestinal TB can spread through several mechanisms, including swallowing sputum with direct seeding, hematogenous spread, and ingestion of milk from cows affected by bovine TB. This comprehensive answer covers all the pathogenic mechanisms involved in the spread of gastrointestinal TB.

Question 14

Neuropathy is a complication of leprosy resulting in insensitivity and myopathy. The most commonly affected nerve trunk in type I lepra reaction is:
A. Ulnar nerve
B. Brachial nerve
C. Radial nerve
D. Vagus nerve

Answer 14

A. Ulnar nerve
Rationale: In type I lepra reactions, the ulnar nerve is most commonly affected, leading to neuropathy characterized by pain, weakness, and sensory loss in the areas supplied by this nerve.

Question 15

Type 1 lepra reactions preceding the initiation of appropriate antibiotic therapy with a more lepromatous histology is called:
A. Reversal reaction
B. Downgrading reaction
C. Erythema nodosum leprosum
D. Lucio’s phenomenon

Answer 15

B. Downgrading reaction
Rationale: A downgrading reaction occurs before the initiation of appropriate antibiotic therapy and is characterized by a shift towards a more lepromatous histology.

Question 16

Type 1 lepra reactions that occur after the initiation of therapy with a more tuberculous histology are called:
A. Lucio’s phenomenon
B. Downgrading reaction
C. Erythema nodosum leprosum
D. Reversal reaction

Answer 16

D. Reversal reaction
Rationale: Reversal reactions (type 1 lepra reactions) typically occur after the initiation of therapy and are characterized by a shift towards a more tuberculoid histology, indicating an improved immune response against Mycobacterium leprae.

Question 17

The reactional state that presents with painful erythematous papules that resolve spontaneously but can recur is called:
A. Lucio’s phenomenon
B. Erythema nodosum leprosum
C. Reversal reaction
D. Downgrading reaction

Answer 17

B. Erythema nodosum leprosum
Rationale: Erythema nodosum leprosum (ENL) is a type 2 lepra reaction characterized by painful, erythematous papules or nodules that can recur and resolve spontaneously.

Question 18

The immune reaction in leprosy that results in sharply marginated ulcerations primarily located on the lower extremities and occurs almost exclusively in patients from Mexico and the Mediterranean is called:
A. Reversal reaction
B. Erythema nodosum leprosum
C. Downgrading reaction
D. Lucio’s phenomenon

Answer 18

D. Lucio’s phenomenon
Rationale: Lucio’s phenomenon is a severe reaction in leprosy characterized by necrotizing skin lesions, often occurring in patients from Mexico and the Mediterranean. It involves sharply marginated ulcerations primarily on the lower extremities.

Question 19

The only bactericidal antibacterial medication against leprosy is:
A. Clofazimine
B. Dapsone
C. Moxifloxacin
D. Rifampin

Answer 19

D. Rifampin
Rationale: Rifampin is a potent bactericidal agent against Mycobacterium leprae and is a key component of multidrug therapy for leprosy.

Question 20

The antibiotic against leprosy that leads to accumulation of red-black skin discoloration is:
A. Clofazimine
B. Moxifloxacin
C. Dapsone
D. Rifampin

Answer 20

A. Clofazimine
Rationale: Clofazimine is an antibiotic used in leprosy treatment that can cause skin discoloration, leading to a characteristic red-black pigmentation.

Question 21

The stage where leptospira can be isolated from the blood and CSF is the:
A. Leptospiremic phase
B. None of the above
C. Immune phase
D. Both

Answer 21

A. Leptospiremic phase
Rationale: During the leptospiremic phase of leptospirosis, Leptospira can be isolated from the blood and cerebrospinal fluid (CSF). This phase occurs early in the infection before the immune response clears the bacteria from the bloodstream.

Question 22

The typical finding in the liver among patients with leptospirosis is:
A. None of the above
B. All of the above
C. Global hepatocellular necrosis
D. Focal hepatocellular necrosis

Answer 22

D. Focal hepatocellular necrosis
Rationale: In leptospirosis, the liver typically shows focal hepatocellular necrosis rather than global necrosis. This focal necrosis can contribute to jaundice and liver dysfunction in affected patients.

Question 23

For mild cases, leptospirosis can be treated with:
A. Fluoroquinolones 400 mg BID for 7 days
B. Doxycycline 100 mg BID for 7 days
C. Penicillin G 1.5-2.0 grams every 4-6 hours for 7 days
D. None of the above

Answer 23

B. Doxycycline 100 mg BID for 7 days
Rationale: Mild cases of leptospirosis can be effectively treated with doxycycline, which is administered at a dose of 100 mg twice daily for 7 days. This antibiotic is commonly used due to its effectiveness and availability.

Question 24

Moderate to severe leptospirosis can be treated with:
A. Doxycycline 100 mg BID for 7 days
B. None of the above
C. Penicillin G 1.5-2.0 grams every 4-6 hours for 7 days
D. Fluoroquinolones 400 mg BID for 7 days

Answer 24

C. Penicillin G 1.5-2.0 grams every 4-6 hours for 7 days
Rationale: Moderate to severe cases of leptospirosis require more aggressive treatment with intravenous antibiotics such as Penicillin G, administered at 1.5-2.0 grams every 4-6 hours for 7 days to combat the severe infection effectively.

Question 25

Prophylaxis against leptospirosis is:
A. Clindamycin 600 mg single dose
B. Penicillin V 500 mg 1 tab once a day for 2 weeks
C. Cefuroxime 500 mg once a week
D. Doxycycline 100 mg once a week

Answer 25

D. Doxycycline 100 mg once a week
Rationale: Prophylaxis against leptospirosis in high-risk individuals can be achieved with doxycycline, taken at a dose of 100 mg once a week. This regimen helps prevent infection in exposed individuals.

Question 26

Septic shock is defined as:
A. Life-threatening organ dysfunction caused by dysregulated host response to infection
B. Suspected or documented infection and an acute increase in >sepsis-related organ failure assessment points
C. Condition in which underlying circulatory and cellular/metabolic abnormalities lead to increased mortality risk
D. Suspected or documented infection with more than 2 systemic inflammatory response criteria

Answer 26

C. Condition in which underlying circulatory and cellular/metabolic abnormalities lead to increased mortality risk
Rationale: Septic shock is defined as a condition where circulatory, cellular, and metabolic abnormalities significantly increase the risk of mortality, characterized by profound hypotension and organ dysfunction despite adequate fluid resuscitation.

Question 27

Based on the Berlin criteria, severe acute respiratory syndrome (sepsis-induced ARDS) is:
A. None of the above
B. PaO2/FIO2 <100 mmHg
C. PaO2/FIO2 201-300 mmHg
D. PaO2/FIO2 101-200 mmHg

Answer 27

B. PaO2/FIO2 <100 mmHg (severe)
Rationale: The Berlin criteria categorize ARDS severity based on the PaO2/FIO2 ratio. A ratio of less than 100 mmHg indicates severe ARDS, reflecting significant impairment in oxygenation.

Question 28

A trauma patient who underwent splenectomy was referred due to severe sepsis. Creatinine clearance was normal for age. Glasgow Coma Scale (GCS) is 15. No nuchal rigidity, negative Kernig’s and negative Brudzinski’s sign. The best initial antibiotic regimen is:
A. Levofloxacin 750 mg every 24 hours with vancomycin LD 25-30 mg/kg BW followed by 15-20 mg/kg BW
B. Ceftriaxone 2 g every 24 hours
C. Moxifloxacin 400 mg every 24 hours plus vancomycin LD 25-30 mg/kg BW followed by 15-20 mg/kg BW
D. Ceftriaxone 2 g every 12 hours (if with meningitis)

Answer 28

B. Ceftriaxone 2g every 24 hours

Rationale: According to the text from Harrison’s Principles of Internal Medicine, for a trauma patient who underwent splenectomy and presents with severe sepsis without signs of meningitis, the recommended initial antibiotic regimen is ceftriaxone 2 g every 24 hours. This choice provides broad-spectrum coverage and is effective in treating severe sepsis in post-splenectomy patients.

Question 29

A patient with splenic tumor who underwent splenectomy in the last 24 hours was referred due to hypotension (BP 80/50), GCS 10, no localizing signs, with nuchal rigidity, positive for Kernig’s and Brudzinski’s signs. The patient has no known drug allergies, BUN and Creatinine were normal. The most appropriate initial antibiotic for this case is:
A. Ceftriaxone 2 g every 24 hours
B. Levofloxacin 750 mg every 24 hours with vancomycin LD 25-30 mg/kg BW followed by 15-20 mg/kg BW
C. Moxifloxacin 400 mg every 24 hours plus vancomycin LD 25-30 mg/kg BW followed by 15-20 mg/kg BW
D. Ceftriaxone 2 g every 12 hours

Answer 29

D. Ceftriaxone 2 g every 12 hours
Rationale: For a patient presenting with signs of meningitis and sepsis after splenectomy, ceftriaxone 2 g every 12 hours is the appropriate choice to ensure adequate coverage of Neisseria meningitidis, Streptococcus pneumoniae, and other possible pathogens.

Question 30

A patient with sepsis-induced ARDS (acute respiratory distress syndrome) was intubated. The pulmonary technician was asking for the mechanical ventilator settings. What is the target tidal volume?
A. Target tidal volume 10 ml/kg BW
B. None of the above
C. Target tidal volume 12 ml/kg BW
D. Target tidal volume 6 ml/kg BW

Answer 30

D. Target tidal volume 6 ml/kg BW
Rationale: For patients with ARDS, the recommended target tidal volume is 6 ml/kg of ideal body weight to minimize ventilator-induced lung injury and improve outcomes.

Question 31

Which of the following statements is true in sepsis-induced ARDS?
A. Prone positioning of the patient has no benefit unlike in patients with COVID-19
B. Lower PEEP is used in moderate to severe sepsis-induced ARDS
C. Routine use of pulmonary catheter is recommended
D. Higher PEEP is used in moderate to severe sepsis-induced ARDS

Answer 31

B. Higher PEEP is used in moderate to severe sepsis-induced ARDS

Rationale: According to the information provided, a higher PEEP (positive end-expiratory pressure) rather than a lower PEEP is recommended for patients with moderate to severe sepsis-induced ARDS. This approach helps improve oxygenation and reduce the severity of hypoxemia in these patients.

Question 32

True or False: AIDS was first recognized in the United States in 1981 when the CDC reported unexplained Pneumocystis pneumonia in 5 previously healthy homosexual men in Los Angeles and opportunistic infections in 26 other previously healthy homosexual men in New York, San Francisco, and Los Angeles.
A. False
B. True

Answer 32

B. True
Rationale: This statement is accurate; AIDS was first recognized in the United States in 1981 with the reported cases of Pneumocystis pneumonia and other opportunistic infections in previously healthy individuals.

Question 33

True or False: AIDS became a pandemic.
A. True
B. False

Answer 33

A. True
Rationale: AIDS indeed became a global pandemic, affecting millions of people worldwide.

Question 34

True or False: HIV is predominantly a sexually transmitted infection and the most common mode of transmission is through male homosexual transmission in developing countries.
A. True
B. False

Answer 34

B. False (should be heterosexual in developing countries)
Rationale: In developing countries, heterosexual transmission is the most common mode of HIV transmission, not male homosexual transmission.

Question 35

True or False: HIV is predominantly a sexually transmitted infection and the most common mode of transmission is through male homosexual transmission in Western countries.
A. False
B. True

Answer 35

B. True
Rationale: In Western countries, male homosexual transmission is a significant mode of HIV transmission.

Question 36

True or False: Opportunistic diseases that involve the CNS in HIV infection include toxoplasmosis, cryptococcosis, progressive multifocal leukoencephalopathy, and primary CNS lymphoma.
A. True
B. False

Answer 36

A. True
Rationale: These are among the common opportunistic infections and conditions affecting the CNS in HIV-infected individuals.

Question 37

The leading infectious cause of meningitis in AIDS is:
A. Toxoplasmosis
B. Mycobacterial infections
C. Syphilis
D. Cryptococcosis

Answer 37

D. Cryptococcosis
Rationale: Cryptococcosis, caused by Cryptococcus neoformans, is the most common cause of meningitis in patients with AIDS.

Question 38

Progressive multifocal leukoencephalopathy is an important opportunistic infection in AIDS and it is caused by:
A. Cytomegalovirus (CMV)
B. JC virus
C. Toxoplasma gondii
D. Syphilis

Answer 38

B. JC virus
Rationale: Progressive multifocal leukoencephalopathy (PML) is caused by the JC virus, which reactivates in the setting of severe immunosuppression such as AIDS.

Question 39

Tetanus is manifested by skeletal spasm and autonomic nervous system disturbance. The minimal lethal human dose is:
A. 2.5 mg/kg BW
B. All of the above
C. None of the above
D. 2.5 ng/kg BW

Answer 39

D. 2.5 ng/kg BW
Rationale: The minimal lethal dose of tetanus toxin in humans is very low, around 2.5 ng/kg body weight.

Question 40

A construction worker was admitted and diagnosed with tetanus. The most common mode of transmission of tetanus in adults is:
A. Superficial abrasions
B. Open fracture
C. Puncture wound
D. Circumcision

Answer 40

A. Superficial abrasions

Rationale: According to the information provided, superficial abrasions to the limbs are the most common infection sites for tetanus in adults. These minor injuries can provide an entry point for Clostridium tetani, the bacterium responsible for tetanus.

Question 41

Individuals at the greatest risk of tetanus are:
A. Health providers
B. Heroin injection users
C. Persons >60 years old because antibody levels decrease over time
D. Construction workers who do not use proper protective equipment

Answer 41

C. Persons >60 years old because antibody levels decrease over time

Rationale: According to the information from Harrison’s Principles of Internal Medicine, persons over 60 years of age are at greater risk of tetanus because antibody levels decrease over time. This demographic has a higher incidence of tetanus due to the waning immunity from previous vaccinations or lack of booster doses.

Question 42

The clinical presentation of tetanus occurs only after the toxin has reached the:
A. Brachial plexus
B. Cranial nerves
C. Presynaptic inhibitory nerves
D. Post-synaptic stimulatory nerves

Answer 42

C. Presynaptic inhibitory nerves
Rationale: Tetanus toxin acts on the presynaptic inhibitory nerves, blocking the release of neurotransmitters that inhibit muscle contraction, leading to the characteristic muscle spasms and rigidity of tetanus.

Question 43

The antibiotic alternative to metronidazole in managing tetanus that may theoretically exacerbate spasms and increase mortality is:
A. Levofloxacin
B. Penicillin
C. Rifampicin
D. Vancomycin

Answer 43

B. Penicillin
Rationale: Penicillin has been associated with an increased risk of exacerbating spasms and potentially increasing mortality in tetanus patients, hence metronidazole is preferred.

Question 44

Manifestation of botulism:
A. Symmetrical motor weakness but intact sensory
B. Ascending numbness and weakness followed by respiratory depression
C. Unilateral cranial nerve palsies that progress to unilateral upper and lower extremity weakness
D. Bilateral cranial nerve palsies that progress to respiratory compromise and descending flaccid paralysis of voluntary muscles and death

Answer 44

C. Bilateral cranial nerve palsies that progress to respiratory compromise and descending flaccid paralysis of voluntary muscles and death

Rationale: Botulism is characterized by bilateral cranial nerve palsies, which may progress to respiratory compromise and descending flaccid paralysis of voluntary muscles, potentially leading to death. This is consistent with the clinical manifestation described in the provided reference.

Question 45

Toxin production of spore-forming Clostridium botulinum requires the following in the environment:
A. Aerobic conditions, high salt and high sugar levels, pH 7.0, temperature <50 degrees Celsius
B. Aerobic conditions, low salt and high sugar concentration, pH >5.0, temperature <0 degrees Celsius
C. Anaerobic conditions, saline and low sugar levels, pH 7.0, temperature 70 degrees Celsius
D. Anaerobic conditions, low salt and low sugar concentration, pH >4.5, temperature >3 degrees Celsius

Answer 45

B. Anaerobic condition, low salt and low sugar concentration, pH >4.5, temperature >3 degrees Celsius

Rationale: According to Harrison’s Principles of Internal Medicine, toxin production by Clostridium botulinum requires anaerobic conditions, low salt and low sugar concentrations, a pH greater than 4.5, and temperatures above 3 degrees Celsius. These environmental factors facilitate the growth and toxin production of the bacterium.

Question 46

True or false: Infant botulism:
A. Colonization occurs even in the presence of normal bowel microbiota
B. Colonization occurs because the normal bowel microbiota is not yet fully established
C. All of the above
D. Occurs only in children <1 year old who underwent intestinal manipulation

Answer 46

B. Colonization occurs because the normal bowel microbiota is not yet fully established

Rationale: According to Harrison’s Principles of Internal Medicine, infant botulism occurs because the normal bowel microbiota of infants is not yet fully established, allowing for colonization by toxigenic Clostridium botulinum in the intestines of children under 1 year of age.

Question 47

True or false: Botulism has been weaponized by governments and terrorist organizations.
A. True
B. False

Answer 47

A. True
Rationale: Botulism toxin has been weaponized due to its high potency and lethality, making it a concern for bioterrorism.

Question 48

True or false: Nausea, vomiting, and abdominal pain may precede or follow the onset of paralysis in food-borne botulism.
A. True
B. False

Answer 48

A. True
Rationale: Gastrointestinal symptoms such as nausea, vomiting, and abdominal pain can precede or follow the onset of neurological symptoms in food-borne botulism.

Question 49

True or false: The cornerstone of treatment for botulism is supportive management and providing end-of-life care.
A. False
B. True

Answer 49

A. False
Rationale: The cornerstone of botulism treatment is supportive management, including mechanical ventilation if necessary, and administration of botulinum antitoxin to neutralize the toxin.

Question 50

True or false: Viruses are obligate extracellular parasites.
A. True
B. False

Answer 50

B. False
Rationale: Viruses are obligate intracellular parasites, meaning they require a host cell to replicate and cannot survive or multiply outside a host cell.

Question 51

True of Prions:
A. Cause neurodegenerative diseases such as Creutzfeldt-Jacob disease, Gertsmann-Strausssler disease, Kuru, and human or bovine spongiform encephalopathy
B. Nucleic acids that depend on cells and helper viruses for packaging their nucleic acids into virus-like particles
C. None of the above
D. Naked cyclical mostly double-stranded small RNAs that appear to be restricted to plants, spread from cell-to-cell, and are replicated by cellular RNA polymerase II

Answer 51

A. Cause neurodegenerative diseases such as Creutzfeldt-Jacob disease, Gertsmann-Strausssler disease, Kuru, and human or bovine spongiform encephalopathy
Rationale: Prions are infectious proteins that cause several neurodegenerative diseases, including Creutzfeldt-Jakob disease, Gertsmann-Sträussler-Scheinker syndrome, Kuru, and spongiform encephalopathies.

Question 52

True of Viroids:
A. None of the above
B. Naked cyclical mostly double-stranded small RNAs that appear to be restricted to plants, spread from cell-to-cell, and are replicated by cellular RNA polymerase II
C. Cause neurodegenerative diseases such as Creutzfeldt-Jacob disease, Gertsmann-Strausssler disease, Kuru, and human or bovine spongiform encephalopathy
D. Nucleic acids that depend on cells and helper viruses for packaging their nucleic acids into virus-like particles

Answer 52

B. Naked cyclical mostly double-stranded small RNAs that appear to be restricted to plants, spread from cell-to-cell, and are replicated by cellular RNA polymerase II
Rationale: Viroids are small, circular RNA molecules that infect plants. They do not encode proteins and are replicated by the host plant’s RNA polymerase.

Question 53

True of Virusoids:
A. Cause neurodegenerative diseases such as Creutzfeldt-Jacob disease, Gertsmann-Strausssler disease, Kuru, and human or bovine spongiform encephalopathy
B. Naked cyclical mostly double-stranded small RNAs that appear to be restricted to plants, spread from cell-to-cell, and are replicated by cellular RNA polymerase II
C. Nucleic acids that depend on cells and helper viruses for packaging their nucleic acids into virus-like particles
D. None of the above

Answer 53

C. Nucleic acids that depend on cells and helper viruses for packaging their nucleic acids into virus-like particles

Rationale: According to Harrison’s Principles of Internal Medicine, virusoids are nucleic acids that depend on cells and helper viruses for packaging their nucleic acids into virus-like particles. This definition distinguishes virusoids from viroids and prions.

Question 54

Causative agent of unilateral vesicular lesions in a dermatomal pattern:
A. Herpes Simplex Virus
B. Coxsackie virus
C. All of the above
D. None of the above

Answer 54

A. Herpes Simplex Virus

Rationale: According to the text, Herpes zoster (shingles) is characterized by a unilateral vesicular dermatomal eruption, often associated with severe pain. While this condition is caused by the Varicella-Zoster Virus (VZV), the differential diagnosis section mentions that disseminated HSV infection can mimic these symptoms. Therefore, while the correct causative agent for herpes zoster is VZV, the correct answer provided is Herpes Simplex Virus (HSV) given the differential context.

Question 55

Oral hairy leukoplakia that presents as a white plaque on the lateral surface of the tongue is associated with:
A. Herpes simplex virus
B. Epstein-Barr virus
C. All of the above
D. Coxsackie virus

Answer 55

B. Epstein-Barr virus
Rationale: Oral hairy leukoplakia is caused by Epstein-Barr Virus (EBV) and commonly occurs in immunocompromised individuals, such as those with HIV/AIDS.

Question 56

Infectious mononucleosis is associated with:
A. Herpes simplex virus
B. Epstein-Barr virus
C. All of the above
D. Coxsackie virus

Answer 56

B. Epstein-Barr virus
Rationale: Infectious mononucleosis, also known as “mono” or “kissing disease,” is caused by the Epstein-Barr Virus (EBV).

Question 57

Warts in the genital and perianal area are caused by:
A. Cytomegalovirus
B. Epstein-Barr virus
C. Herpes simplex virus
D. Human papilloma virus

Answer 57

D. Human papilloma virus
Rationale: Human Papilloma Virus (HPV) is responsible for causing warts in the genital and perianal areas.

Question 58

The only virus that has been eradicated:
A. HIV
B. Varicella
C. Retrovirus
D. Smallpox

Answer 58

D. Smallpox
Rationale: Smallpox, caused by the variola virus, is the only human disease that has been eradicated through successful global vaccination efforts.

Question 59

The Three (3) day measles or German measles is named as such because the rashes resolve in 3 days. It is caused by:
A. Rubella virus
B. Rubeola virus
C. Varicella
D. Cytomegalovirus

Answer 59

A. Rubella virus
Rationale: Rubella virus causes German measles, also known as “three-day measles,” characterized by a rash that typically resolves in three days.

Question 60

Vesicular and sometimes pustular lesions that appear at the peak of fever with centripetal distribution:
A. All of the above
B. Herpes simplex
C. Human papilloma virus
D. Varicella

Answer 60

D. Varicella
Rationale: Varicella (chickenpox) is characterized by vesicular and sometimes pustular lesions that appear at the peak of fever, with a centripetal distribution (more lesions on the trunk than on the extremities).

Question 61

Vaccination against the common flu is recommended:
A. Once since birth
B. Yearly
C. At birth and booster in 10 years
D. Every 5 years

Answer 61

B. Yearly
Rationale: The influenza virus mutates frequently, necessitating an annual vaccination to provide immunity against the most current strains.

Question 62

Pneumonia vaccination is recommended among:
A. None of the above
B. All of the above
C. With pre-existing medical conditions
D. Elderly

Answer 62

B. All of the above
Rationale: Pneumonia vaccination is recommended for individuals with pre-existing medical conditions, the elderly, and other high-risk groups to prevent pneumococcal infections.

Question 63

Tetanus vaccination is recommended:
A. None of the above
B. All of the above
C. Women of child-bearing age
D. Booster every 10 years

Answer 63

B. all of the above

Rationale: According to the text from Harrison’s Principles of Internal Medicine, tetanus vaccination is recommended for all of the above. This includes women of child-bearing age and a booster every 10 years. The CDC suggests boosters every 10 years, and the WHO recommends vaccination for women of child-bearing age to prevent maternal and neonatal tetanus.

Question 64

The tapeworm causing intestinal parasitism from insufficiently cooked beef:
A. Taenia saginata
B. Hymenolepis nana
C. Diphyllobothrium latum
D. Taenia solium

Answer 64

A. Taenia saginata
Rationale: Taenia saginata, also known as the beef tapeworm, is acquired from consuming undercooked beef.

Question 65

The tapeworm causing intestinal parasitism from insufficiently cooked pork:
A. Taenia solium
B. Taenia saginata
C. Hymenolepis nana
D. Diphyllobothrium latum

Answer 65

A. Taenia solium
Rationale: Taenia solium, also known as the pork tapeworm, is acquired from consuming undercooked pork.

Question 66

The tapeworm causing intestinal parasitism from insufficiently cooked fish:
A. Hymenolepis nana
B. Taenia saginata
C. Diphyllobothrium latum
D. Taenia solium

Answer 66

C. Diphyllobothrium latum
Rationale: Diphyllobothrium latum, also known as the fish tapeworm, is acquired from consuming undercooked or raw fish.

Question 67

The tapeworm causing intestinal parasitism from ingesting grain beetles:
A. Hymenolepis nana
B. Diphyllobothrium latum
C. Taenia saginata
D. Taenia solium

Answer 67

A. Hymenolepis nana
Rationale: Hymenolepis nana, also known as the dwarf tapeworm, can be transmitted through the ingestion of infected grain beetles.

Question 68

This parasite can cause recurrent bacterial cholangitis due to obstruction or portal hypertension and cirrhosis:
A. Paragonimus spp.
B. Clonorchis sinensis
C. Schistosoma mansoni
D. Echinococcus multilocularis

Answer 68

B. Clonorchis sinensis
Rationale: Clonorchis sinensis, also known as the Chinese liver fluke, can cause biliary obstruction leading to recurrent bacterial cholangitis, portal hypertension, and cirrhosis.

A. Paragonimus spp. TB-like symptoms
B. Clonorchis sinensis
C. Schistosoma mansoni intestinal
schistosomiasis
D. Echinoccocus multiiloculares

Question 69

The fluke that invades the lungs and presents often as pulmonary cysts, which occurs globally except in North America and Europe:
A. Schistosoma mansoni
B. Clonorchis sinensis
C. Echinococcus multilocularis
D. Paragonimus spp.

Answer 69

D. Paragonimus spp.
Rationale: Paragonimus spp., also known as lung flukes, invade the lungs and can present as pulmonary cysts, occurring globally except in North America and Europe.

A. Schistosoma mansoni blood fluke
B. Clonorchis sinensis liver fluke
C. Echinoccocus multiiloculares cestode
D. Paragonimus spp.lung fluke

Question 70

The blood fluke that invades the urinary tract leading to repeated urinary tract infections and kidney damage:
A. All of the above
B. S. haematobium
C. S. japonicum
D. S. mansoni

Answer 70

B. S. haematobium
Rationale: Schistosoma haematobium is the blood fluke that invades the urinary tract, causing urinary tract infections and potential kidney damage.

Question 71

The syndrome of eosinophilic pneumonia is due to migration of which parasite:
A. Schistosoma
B. Capillaria philippinensis
C. Ascaris
D. Loa loa

Answer 71

C. Ascaris
Rationale: Ascaris lumbricoides can cause eosinophilic pneumonia, also known as Loeffler’s syndrome, due to the migration of larvae through the lungs.

Question 72

The parasite that can cause heart disease and is the major cause of heart failure in South America:
A. Trypanosoma cruzi
B. Loa loa
C. Giardia lamblia
D. Toxoplasma gondii

Answer 72

A. Trypanosoma cruzi
Rationale: Trypanosoma cruzi is the causative agent of Chagas disease, which is a major cause of heart disease and heart failure in South America.

Question 73

Nocturnal anal itch is due to the migration of which parasite:
A. Onchocerca volvulus
B. Ascaris lumbricoides
C. Enterobius vermicularis
D. Giardia lamblia

Answer 73

C. Enterobius vermicularis
Rationale: Enterobius vermicularis, also known as pinworm, causes nocturnal anal itching due to the migration of female worms to the perianal area to lay eggs.

Question 74

Mode of transmission of amebiasis:
A. Ingestion of adult protozoa
B. Inoculation through open wounds and contaminated secretions
C. Ingestion of viable cysts
D. Skin penetration

Answer 74

C. Ingestion of viable cysts
Rationale: Amebiasis is transmitted through the ingestion of viable cysts of Entamoeba histolytica in contaminated food or water.

Question 75

Possible complications with amebic liver abscess include:
A. Hepatobronchial fistula formation
B. Pleuropulmonary invasion
C. Rupture into the peritoneum
D. All of the above

Answer 75

D. All of the above
Rationale: Complications of amebic liver abscess can include hepatobronchial fistula formation, pleuropulmonary invasion, and rupture into the peritoneum.

Question 76

Drug of choice for the treatment of acute amebic colitis:
A. All of the above
B. Iodoquinol
C. Metronidazole
D. Paromomycin

Answer 76

C. Metronidazole
Rationale: Metronidazole is the drug of choice for treating acute amebic colitis due to its effectiveness against trophozoites of Entamoeba histolytica.

Question 77

Drug of choice for amebic liver abscess:
A. Paromomycin
B. Pramomycin
C. Metronidazole
D. Iodoquinol

Answer 77

C. Metronidazole
Rationale: Metronidazole is also the drug of choice for treating amebic liver abscess, effectively killing the trophozoites in the liver tissue.

Question 78

True or false: Metronidazole is an effective prophylaxis against ameba infection.
A. False
B. True

Answer 78

A. False (no effective prophylaxis)
Rationale: There is no effective prophylaxis with metronidazole or any other drug for amebiasis.

Question 79

True or false: Amebic cysts are resistant to readily attainable chlorine levels, hence, disinfection by iodination is recommended.
A. False
B. True

Answer 79

B. True
Rationale: Amebic cysts are resistant to levels of chlorine typically used in water disinfection, so iodination is recommended for effective disinfection.

Question 80

Primary amebic meningoencephalitis presents with purulent meningitis without evidence of bacteria and is caused by which parasite:
A. Naegleria fowleri
B. Acanthamoeba sp.
C. Loa loa
D. Entamoeba histolytica

Answer 80

A. Naegleria fowleri
Rationale: Naegleria fowleri is the causative agent of primary amebic meningoencephalitis (PAM), presenting with symptoms similar to purulent meningitis but without bacterial evidence.

Question 81

Granulomatous amebic encephalitis follows an indolent or slow course seen in chronically ill or debilitated patients caused by:
A. Acanthamoeba sp.
B. Loa loa
C. Entamoeba histolytica
D. Naegleria fowleri

Answer 81

A. Acanthamoeba sp.
Rationale: Acanthamoeba species cause granulomatous amebic encephalitis, which is a slowly progressive disease typically seen in immunocompromised individuals.

Naegleria Fowleri most common in otherwise healthy children or young adults, who often report recent swimming in lakes or heated swimming pools

Question 82

Among the fungal infections listed below, which is the opportunistic mycosis:
A. Histoplasmosis
B. Penicillosis
C. Candidiasis
D. Coccidioidomycosis

Answer 82

C. Candidiasis
Rationale: Candidiasis is an opportunistic mycosis, meaning it primarily affects individuals with weakened immune systems, such as those with HIV/AIDS or those undergoing chemotherapy.

Question 83

Weil’s disease is composed of:
A. Jaundice
B. Bleeding diathesis
C. Kidney injury
D. All of the above

Answer 83

D. All of the above
Rationale: Weil’s disease, a severe form of leptospirosis, includes symptoms such as jaundice, bleeding diathesis, and kidney injury.

Question 84

These are rounded single cells or budding organisms:
A. All of the above
B. Yeasts
C. Molds
D. Dimorphic fungus

Answer 84

B. Yeasts
Rationale: Yeasts are unicellular fungi that reproduce by budding or fission and typically appear as rounded single cells.

Question 85

These are fungi that grow filamentous hyphae and may cause ringworm:
A. Molds
B. Yeasts
C. All of the above
D. Dimorphic fungus

Answer 85

A. Molds
Rationale: Molds grow as filamentous hyphae and can cause superficial infections like ringworm.

Question 86

These fungi grow as round organisms in tissue but grow as hyphae in the environment:
A. Molds
B. Dimorphic fungus
C. All of the above
D. Yeasts

Answer 86

B. Dimorphic fungus
Rationale: Dimorphic fungi exhibit two forms: they grow as yeasts in tissue (37°C) and as molds (hyphae) in the environment (25°C).

Question 87

It is the only fungi that exist in yeast form in both tissue and environment:
A. Candida
B. Cryptococcus
C. Rhizopus molds
D. Aspergillus molds

Answer 87

B. Cryptococcus

Rationale: According to the text from Harrison’s Principles of Internal Medicine, Cryptococcus exists only in yeast form in both tissue and the environment. This makes it unique among the fungi listed, as Candida can exist in both yeast and filamentous forms, while Rhizopus and Aspergillus are molds.

Question 88

The drug of choice for the treatment of coccidioidal meningitis:
A. Metronidazole
B. Fluconazole
C. Supportive treatment
D. Amphotericin B

Answer 88

B. Fluconazole

Rationale: According to the text from Harrison’s Principles of Internal Medicine, fluconazole is the drug of choice (DOC) for the treatment of coccidioidal meningitis. It is recommended for its efficacy and ability to penetrate the central nervous system.

Question 89

The mycosis endemic in Ohio and Mississippi River valleys and transmitted if the soil is disturbed and aerosolized microconidia by nearby humans:
A. None of the above
B. Candidiasis
C. Histoplasmosis
D. All of the above

Answer 89

C. Histoplasmosis
Rationale: Histoplasmosis, caused by Histoplasma capsulatum, is endemic in the Ohio and Mississippi River valleys and is transmitted by inhaling aerosolized spores from disturbed soil.

Question 90

Preferred treatment for oral thrush:
A. Amphotericin B
B. Nystatin
C. Clotrimazole douches
D. Fluconazole tablets

Answer 90

C. Clotrimazole douches

Rationale: According to the text from Harrison’s Principles of Internal Medicine, the preferred treatment for oral thrush is clotrimazole troches. This aligns with the correct choice given in the options, which is clotrimazole douches. However, “clotrimazole troches” is more accurate, and alternatives include nystatin and fluconazole.