A previously healthy 15-year-old white boy presented with a 4-week history of cough and fever. At admission, he had a productive cough with thick, yellow sputum; intermittent daily temperatures of 38.5°C; night sweats; malaise; anorexia; and weight loss of approximately 4.5 kg. At the onset of illness, three siblings had had sore throats, but he had no history of a sore throat, recent travel, or exposure to animals. He had been smoking one pack of cigarettes per day for 2 years. Three months before admission, he was diagnosed as having mild asthma, and intermittently used inhaled epinephrine. He reported exposure to a friend who was diagnosed with tuberculosis the previous year and was receiving antituberculosis medications.
Vital signs on admission to the hospital were as follows: temperature, 39.4°C; heart rate, 120 beats per minute; respiratory rate, 32/min; and blood pressure, 110/60 mm Hg. Physical examination revealed a pale, thin, ill-appearing