Haemophilus influenzae pneumonia in young adults with AIDS, ARC, or risk of AIDS

Since the acquired immunodeficiency syndrome (AIDS) was first described in 1981, we have observed an increasing number of cases of Haemophilus influenzae pneumonia, particularly in young adult patients. To confirm this observation, we systematically identified and reviewed all cases of H. influenzae pneumonia that occurred in adult patients recently hospitalized at our institution.

Using a strict case definition, we identified all cases of adult H. influenzae pneumonia that were observed during a recent 32-month period at our institution, a large teaching hospital in New York City. We further reviewed each case record for evidence of AIDS, AIDS-related complex (ARC), or risk of AIDS.

H. influenzae pneumonia was diagnosed in 51 adults. Thirty-four cases occurred in young adults (mean age = 33.9 years) with AIDS risk factors, including 23 (67 percent) intravenous drug abusers, six (18 percent) homosexual men, and five (15 percent) with both risks. Nine patients (26 percent) had a previous or concurrent diagnosis of AIDS, four (12 percent) developed AIDS later, and 13 (38 percent) others had ARC. The common presenting symptoms in young adult patients with H. influenzae pneumonia were fever (100 percent), productive cough (100 percent), chest pain (53 percent), and dyspnea (47 percent). Lung consolidation was detected on physical examination in 20 (59 percent), and chest radiograph demonstrated unilateral infiltrates in 18 (53 percent) and bilateral infiltrates in 16 (47 percent), with pleural effusions in three (nine percent). Most patients had an elevated white blood cell count (mean = 9.6 X 10(9)/liter) with a left shift in 22 (65 percent), and hypoxia on room air (mean partial pressure of oxygen = 69 mm Hg). Four patients with H. influenzae pneumonia and coexisting Pneumocystis carinii pneumonia had diffuse, bilateral infiltrates on chest radiograph, with significantly more dyspnea and a higher serum lactate dehydrogenase level than the others. All but one patient showed improvement with appropriate therapy.

We conclude that potentially serious pneumonia caused by H. influenzae occurs in young adult patients with AIDS, ARC, or AIDS risk.