Etiology

A 22-year-old American woman working in southern Ukraine is hospitalized with a sore throat. Physical examination of the throat reveals a tonsillar and posterior pharyngeal membrane. What is the etiology?

Corynebacterium diphtheriae

A 54-year-old woman has diphtheria caused by a toxigenic strain of Corynebacterium ulcerans. Which of the following is the most likely explanation for the production of toxin by C. ulcerans?

It carries the same bacteriophage as C. diphtheria.

A 7-year-old female has a 1-week history of fever, sore throat, and headache. Which pathogen would most likely grow from her throat culture?

Streptococcus pyogenes

A patient has a high fever and displays strawberry-like appearance of her tongue. Which of the following is she likely suffering from?

scarlet fever

If you mix a patient's serum, toxin, and mammalian cells and the cells survive, you know the patient has antibodies against __________.

C. diphtheriae toxin

A 45-year-old male demolition worker is hospitalized with an acute respiratory illness. Yeast cells are seen in microscopic examination of a lung biopsy, and a mold is cultured. What is the etiology?

Histoplasma capsulatum

A 35-year-old male is hospitalized for cough, fever, and shortness of breath. He is HIV-positive. Bronchial washings reveal cysts. What is the etiology?

Pneumocystis

A 30 year old homeless male is examined for a persistent cough with sputum production. He is HIV-positive and has a low CD4+ count. Acid-fast rods grow from sputum. The recommended treatment is with _____

isoniazid and rifampin

A physician receives a lab report indicating that acid-fast bacilli were found in sputum from a patient with a lower respiratory tract infection. The physician suspects __________.

tuberculosis

An 81-year-old female has a mass in her lower-left lung. Her tuberculin skin test is negative. Microscopic examination of her lung biopsy reveals large, ovoid cells. The patient has ________.

Histoplasmosis

A 90-year-old patient is diagnosed with pneumonia. Microscopic examination shows a bacterial agent that lacks cell walls. What is the etiology cause of the patient's pneumonia?

Mycoplasma pneumonia

An outbreak of pneumonia occurs in a wing of a hospital housing kidney-transplant patients. The source of infection is traced to the water supply of the air conditioner. This case describes transmission of which of the following?

Legionella pneumophila

A patient has a rapid onset of fever, chills, labored breathing, and sore throat. He recently returned from Mexico, where he drank local water and stayed in an air-conditioned room. Several weeks ago, he purchased a parrot. After a physical exam, his physician prescribes tetracycline. What is the cause of the patient's illness?

Chlamydia psittaci

Some respiratory diseases are best diagnosed by a gram-stained smear and/or culture, while others are best diagnosed by specific antigen testing or by detecting IgM antibodies. Which of the following respiratory diseases is best diagnosed by doing a specific IgM titer?

Mycoplasma pneumoniae

A man found living in a rat-infested building develops a high fever and swollen lymph nodes in the armpit and groin, called buboes. A gram-negative bacillus is isolated from the patient. and the rats are found to be infested with Xenopsylla cheopsis. What is the disease?

Bubonic Plague

A patient has flu-Like symptoms and a bull's eye rash on his leg. Investigation reveals that he had been hiking in Connecticut and had been bitten by two ticks. What is the diagnosis?

Lyme Disease

You see flagellated cells in microscopic examination of feces from a patient with diarrhea. You conclude the etiology is:

Giardia

A patient has an STD characterized by sporadically recurring, painful, fluid-filled blisters.

Genital Herpes

The CDC recommends that pregnant women tested and offered antibiotic therapy prior to delivery if they are vaginal carriers of:

Streptococcus agalactiae