A 52-year-old woman has had a chronic cough for the past 2 years, accompanied by a small amount of occasionally blood-streaked, whitish sputum. On physical examination, her temperature is 37.9deg C, pulse is 72/min, respirations are 22/min, and blood pressure is 125/80 mm Hg. Crackles are heard on auscultation over the upper lung fields. Heart sounds are faint, and there is a 15 mm Hg inspiratory decline in systolic arterial pressure. The chest radiograph shows prominent heart borders with a “water bottle” configuration. Pericardiocentesis yields 200 mL of the bloody fluid. Infection with which of the following organisms is most likely to produce these findings?
Correct Answer: Mycobacterium tuberculosis
Description: The clinical features are those of pericarditis with effusion, and the most common causes of hemorrhagic pericarditis are metastatic carcinoma and tuberculosis. An effusion of this size is sufficient to produce some cardiac tamponade that diminishes cardiac output; the paradoxical drop in pressure (more than 10 mm Hg) is called pulsus paradoxus and can be caused by pericarditis and by tamponade. Candida is a rare cardiac infection in immunocompromised individuals. Coxsackieviruses are known to cause myocarditis. Group A streptococci are responsible for rheumatic fever; in the acute form, rheumatic fever can lead to fibrinous pericarditis, and in the chronic form, it can lead to serous effusions from congestive heart failure. Staphylococcus aureus is most often a cause of infective endocarditis.
Category:
Pathology
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