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Bacterial Diseases

Five post office workers have all come down with a similar respiratory illness characterized by low-grade fever, chills, cough, dyspnea on exertion, and generalized malaise. A chest radiograph taken on one of them shows mediastinal edema and a sputum Gram stain shows WBCs and large gram-positive rods. A blood culture also shows gram-positive rods. This infection was most likely acquired by:

A. Inhalation of vegetative bacteria

B. Inhalation of conidia

C. Inhalation of spores

D. Traumatic inoculation of vegetative bacteria

E. Traumatic inoculation of spores

ANSWER: C – This is a case of anthrax acquired by inhalation of spores planted in envelopes.

Answer analysis:

A. Vegetative bacteria would not survive long enough.

B. Conidia are fungal structures similar to spores

C. CORRECT – This is bioterrorism

D. See A

E. This would lead to localized lesion at that site

A young girl in the former Soviet republic of Georgia has a severe sore throat and multiple white plaques in the back of her throat. She is acutely ill and has a heart murmur. She has had only one set of her childhood immunizations because the supplies in the village where she lives had run out. The manifestations in her throat and heart are due to a toxin which:

A. Stimulates adenylate cyclase

B. Inserts into sarcolemma membranes

C. Inhibits protein synthesis

D. Inhibits acetylcholine release

E. Stimulates cytokine release

ANSWER: C – This is a case of diphtheria

Answer analysis:

A. A mechanism for toxins that usually stimulate secretion like diarrhea

B. M protein injury mechanism in rheumatic fever

C. CORRECT – Diphtheria toxin (DT), leads to cell death

D. Cause of paralysis in botulism

E. A range of activities (good and bad) depending on the cells cytokines reach

Over half the persons attending a banquet developed a vague febrile illness 2 to 5 days later. Most of those who sought medical aid had the same organism isolated from their bloodstream. Food histories incriminate dairy products but it appears certain they were kept refrigerated right up to the serving time. Which of the following is most likely to be the cause?

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