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Question 21#

A 22-year-old male patient complains of fever and shortness of breath. There is no pleuritic chest pain or rigors and no sputum production. A chest x-ray shows diffuse perihilar infiltrates. The patient worsens while on azithromycin. A methenamine silver stain shows cystlike structures. Which of the following is correct? 

A) Definitive diagnosis can be made by serology
B) The organism will grow after 48 hours
C) History will likely provide important clues to the diagnosis
D) Cavitary disease is likely to develop
E) The infection is unlikely to recur

Correct Answer is C


Patients with Pneumocystis jiroveci (formerly carinii) frequently present with shortness of breath and no sputum production. The interstitial pattern of infiltrates on chest x-ray distinguishes the pneumonia from most bacterial infections. Diagnosis is made by review of methenamine silver stain. Serology is not sensitive or specific enough for routine use. The organism does not grow on any media. Cavitation is quite unusual. The history is likely to suggest a risk factor for HIV disease. The disease commonly recurs in patients with CD4 counts below 200/µL unless prophylaxis (usually with trimethoprim-sulfamethoxazole) is employed.