Bacterial Infections, Part 1 (Gram +, Infections of Childhood, STDs, Spirochetes)

Question 1

A 24-year-old woman presents with severe vomiting, abdominal cramps and diarrhea 2 hours after eating out. She reports that the macaroni salad was delicious.

Answer 1

• S. aureus
• Staph. food poisoning usually present less than 6 hours after a meal.
• Preformed, heat-stable enterotoxin B is present.

Question 2

A 28-year-old homeless man presents with high fever, chills, productive cough, hemoptysis and right-sided chest pain. A systolic ejection murmur is heard. You also find signs of IV drug abuse. A. What is the etiology of his heart disease? B. What pathogen is the likely source?

Answer 2

A. Bacterial Endocarditis
B. S. aureus

-S. aureus causes suppurative infections of the skin, joints, and bones. The most common source of this bacteria is the skin, and it is a common cause of bacterial endocarditis.

Question 3

Bacterial agent associated with toxic shock syndrome in pregnant women?

Answer 3

Staphylococcus aureus

Question 4

Major bacterial cause of infections associated with the introduction of medical devices?

Answer 4

Coagulase-negative staphylococci

Question 5

Agent that causes rheumatic fever and acute glomerulonephritis?

Answer 5

Streptococcus pyogenes

Question 6

11-year-old boy presents with a 5 day history of pharyngitis and has punctate red rashes on his skin. Physical exam also reveals erythematous swelling of the skin. You’re an intern, and alone and scared. You order a blood test which reveals an elevated titer of antistreptolysin O antigen. The test supports what causative agent?

Answer 6

Streptococcus pyogenes.

• Often causes acute pharyngitis.
• Punctate rash is Scarlet Fever, caused by an erythogenic toxin which follows pharyngitis most commonly.
• Erythematous swelling=erysipelas.
• Streptolysin S and O are important markers.

Question 7

A 28 year-old man presents with sudden onset of fever, chills, and a productive cough (blood-tinged sputum). He complains that his right ear hurts. Chest X-ray reveals consolidation of the right middle lobe. Sputum culture is Gram +. Pathogen?

Answer 7

Streptococcus pneumoniae

-Major cause of lobar pneumonia
-Pyogenic infections: Pneumonia, otitis media, sinusitis, menigitis.
Lobar pneumonia stages: 1. congestion/edema 2. red hepatization 3. gray hepatization 4. resolution.

Question 8

Most common cause of neonatal pneumonia, meningitis and sepsis?

Answer 8

Group B steptococci.

Question 9

A 5-year-old boy presents with fever and a sore throat. You observe a dirty-gray membrane on the tonsils and posterior pharynx.

Answer 9

Corynebacterium diptheriae.

-A necrotizing upper respiratory infection associated with gray, leathery membranes of sloughed epithelium.

Question 10

On a busy day in the clinic, you overhear a child in the waiting room with an uncontrollable cough, which is heavily labored on inhalation. Today is a good day for___?

Answer 10

Bordetella pertussis. Whooping cough.

-4-5 week cough characterized by a deep “whooping” sound as the patients tried to take a breath.

Question 11

A 3-year-old boy presents with high fever, sore throat, hoarse voice and acute respiratory distress. His neck is stiff. He also has epiglottitis. What is the most likely cause?

Answer 11

Haemophilus influenzae

• Leading cause of bacterial meningitis in children.
• Also effects ear, sinus, face, EPIGLOTTIS, LUNGS, and joints.

Question 12

Gram negative coccus that causes pyogenic meningitis and overwhelming shock?

Answer 12

Neisseria meningitidis.

Question 13

A 13-year-old kid develops fever, generalized rash, and a stiff neck. The child develops shock and dies. Autopsy reveals bilateral adrenal hemorrhages. Suspected pathogen?

Answer 13

Neisseria meningitidis.

• Causes pyogenic meningitis and overwhelming shock.
• Waterhouse-Friderichsen syndrome

Question 14

A 21-year-old febrile man complains of terrible pain upon urination. His right knee is also sore, but he suggests it’s from playing football with the guys. Blood test reveals elevated WBC count. What etiologic agent may tie all this up?

Answer 14

Neisseria gonorrhea.

• Acute suppurative infection that presents as urethritis in men, and endocervicitis in women.
• Septic arthritis may result from hematogenous spread.

Question 15

A 30-year-old man presents with inguinal swelling and painless penile and perianal ulcers. He is sexually active. Biopsy from a skin lesion reveals organisms clustered in large macrophages.

Answer 15

Granuloma inguinale

• Sexually transmitted, chronic, superficial ulceration of the genital, inguinal, and perianal region caused by Calymmatobacterium granulomatis.
• Donovan bodies = microorganisms clustered within large macrophages.

Question 16

A 34-year-old immigrant from Guinea-Bissau is concerned about his sexual life and demands to see you about it. On exam, he presents a painful, well defined genital ulcer. You notice he also has painful lymphadenopathy. Pathology from a swab reveals a gram negative bacillus.

Answer 16

Chancroid, Haemophilus ducreyi.

• Well defined genital ulcer.
• Painful lymphadenopathy in 30-60% of patients.

Question 17

A 32 year old male was diagnosed at an emergency room with syphilis, but was lost to follow-up after he refused treatment. 20 years later he complained of a “ripping” feeling in his chest, collapsed, and died of an ascending aortic dissection. What observation will be made on the autopsy? In what stage of syphilis is this present?

Answer 17

Rough and pitted aortic intima (tree-bark) with a weakened, stretched aorta and an aortic valve that no longer occludes the border between left ventricle and aorta. This is an advanced form of Tertiary Syphilis known as syphilitic aortitis.

Question 18

A 27 year old female presents with a single, ulcerated lesion on her vulva that has been present for 3 days. The border of the ulcer is firm and raised. During the sexual history, the patient notes that she has recently changed partners. What is the pathogen?

Answer 18

Syphilis (Treponema pallidum) – the ulcer with firm, raised borders is the chancre, and is usually solitary.

Question 19

A 41 year old male presents with a macropapular rash of the back, arms, and palms. Upon examination, small lesions in the roof of the mouth are also observed and very small patches of hair have recently fallen out around popular lesions on the scalp. What pathogen is responsible? What stage is this?

Answer 19

Syphilis (Treponema pallidum) – secondary syphilis. You may also observe exudative plaques in the genital areas and coin-like lesions (syphilids) on the face and perineum.

Question 20

A three year old presents with chronic rhinitis and a desquamative rash. On examination, the nose appears slightly saddle shaped and the legs have anterior bowing. What is your diagnosis?

Answer 20

Congenital syphilis. Anterior bowing is ‘saber shins,’ and you may also observe peg-shaped upper incisors (Hutchinson teeth). Treat with penicillin.

Question 21

While traveling through villages in Borneo with Medecins Sans Frontieres, you observe children that have large (2-5cm) papillomas and numerous smaller, scaly papillomas on exposed areas of the skin. Some walk with an outward bow to their legs due to sores on their feet. What pathogen causes these lesions?

Answer 21

Treponema pertenue causing Yaws, the term for the cutaneous papillomas. The outward bow in the legs is due to ‘crab yaws.’

Question 22

A recent immigrant from Ghana brought his sister, who was visiting from his home country, to your clinic. Her 5 month old son had recently developed mouth lesions, and her breast now had an ulcerating lesion with firm, raised borders. Exam of the baby showed the lesions in the mucosa of the mouth as well as gummas extending into the trachea as far as could be readily seen. What pathogen is responsible?

Answer 22

Bejels, also known as endemic syphilis. It can also spread via mouth-to-mouth and utensil sharing.

Question 23

While traveling down the Amazon, you notice that your guides, a husband-wife team, have many spots on their skin that are multicolored. You relax, knowing that the long-term skin-to-skin contact necessary for transmission will not occur on this two week vacation. What is the pathogen and disease?

Answer 23

Pinta due to Treponema carateum

Question 24

Your 19 year old male patient comes to your office on Wednesday the 5th of June after a long hike the weekend prior. He is concerned as he has an erythematous macule on his lower right leg. He complains of fatigue and some minor joint pain. What is he worried that he has contracted? What is the pathogen?

Answer 24

Lyme disease due to B burgdorferi transmitted by a tick bite. This early stage is Stage 1, and the erythema chondricum migrans will probably develop the ‘bullseye’ appearance over the next several days to weeks.

Question 25

A long-time outdoorsman from Connecticut is referred to your cardiology practice, where you diagnose an atrioventricular block due to myocarditis. Although it is hard to tell through the beard, you think you might see a minor facial palsy as well. What test will you run?

Answer 25

IgG titers for Lyme disease (B burgdorferi) antigens due to symptoms classically seen in the Stage 2 form of the disease

Question 26

A retired 53 year old Army veteran who had a long posting at Fort Drum (rural northern New York) presents in your practice with symptoms similar to rheumatoid arthritis (including mononuclear infiltrate of the knee synovium), but he also has recent neurologic changes in behavior and memory loss. What pathogen is high on your differential diagnosis?

Answer 26

B burgdorferi presenting with Stage 3 Lyme disease.

Question 27

A 20 year old male presents with fever, chills, and myalgias several days after going duck hunting at the edge of a local swamp. What pathogen will you rule out due to your concern for hepatic or renal failure?

Answer 27

Leptospira due to the risk of Weil disease in 10% of cases, and its 5-30% mortality rate (Remember the MLC case with the 4-wheeler!). Is seen as IgM pleocytosis in the CSF followed by hepatic/renal damage

Question 28

While working with migrant worker camps in Peru during the coldest part of winter, you start to see cases with high fever associated with arthralgias and myalgias. On examination, many patients have skin petechiae and conjunctival hemorrhage. Of note is the disappearance of symptoms after a few days in many cases and then reappearance in a lesser form a week later. What do you suspect?

Answer 28

Relapsing fever due to lice carrying Borrelia recurrentis. Remember that the epidemic form has only louse-human interactions, while the endemic form relies on rodent reservoirs and is transmitted by ticks. Major spleen damage is seen in fatal cases.

Question 29

Taking a break from your work with Medecins Sans Frontieres, you take a look at the foot of one of your guides since he has a non-healing scratch. You are surprised to see a large ulcer where the skin has sloughed off and now has raised borders and a gray, putrid exudate. What could have acted so destructively in such a short time?

Answer 29

Tropical phagedenic ulcer, with Bacillus and Treponema. May require plastic surgery to restore function.

Question 30

You are called in to see a peds case at the refugee clinic. A recent arrival had been in isolation for suspected measles, and now a papule on his cheek has grown to begin eroding the face down to the bone. You immediately start a regimen of antibiotics and set up a consult with plastic surgery. Why?

Answer 30

You suspect Noma, or gangrenous stomatitis, which affects malnourished children with recent infections. The cheek is the most likely location of the initial lesion, and the necrosis and disfigurement can be treated if early enough, but is generally permanently damaging.