A 27 -year-old woman from Trinidad presented at a rehabilitation facility with a 3-day history of fever and shortness of breath. Six months prior to hospital admission, she had received a diagnosis of HIV infection at an outside institution, at which time antiretroviral therapy was initiated. Pneumocystis carinii pneumonia (PCP) prophylaxis was not initiated at that time. Her CD4+ T-cell count at the time of diagnosis is unknown. One month prior to hospital admission, she began treatment for a presumptive diagnosis of PCP with trimethoprim/sulfamethoxazole and prednisone at another hospital. She improved and was transferred to a chronic care facility to complete her course of therapy. Three days prior to hospital admission, while at the chronic care facility, the patient was completing her therapy and her dose of prednisone was tapered. She subsequently developed a fever of 102°F, shortness of breath, cough with scanty sputum, and abdominal pain in both upper quadrants. She denied having any purulent or bloody sputum, headache, photophobia, chest pain, palpitation, dysphagia, diarrhea, or dysuria. Two days prior to hospital admission, a regimen of broad-spectrum antibiotics was initiated at the chronic care facility, including vancomycin, ceftriaxone, and amikacin, presumably as coverage for nosocomial superinfection. However, her symptoms worsened, and she was transferred to our institution within approximately 24 h of her acute illness. The patient denied any other concurrent medical problems. Her medications at the time of transfer to our institution included multiple antiretroviral medications, prednisone, and the antibiotics mentioned earlier. The patient drinks alcohol occasionally and denied cigarette smoking or illicit drug abuse. The patient migrated from Trinidad 2 years ago. She lived in New York City with her mother and her cousin. She was a babysitter prior to her illness.