Increased risk of bacterial pneumonia in HIV-infected intravenous drug users without AIDS

Although patients with AIDS have been noted to be at risk for bacterial pneumonia as well as opportunistic infections, little is known about the risk of bacterial pneumonia in HIV-infected populations without AIDS. To determine the incidence of bacterial pneumonia in a well defined population of intravenous drug users (IVDUs), and to examine any association with HIV infection, we prospectively studied 433 IVDUs without AIDS, enrolled in a longitudinal study of HIV infection in an out-patient methadone maintenance program. At enrollment, 144 (33.3%) subjects were HIV-seropositive, 289 (66.7%) were seronegative. Over a 12-month period, 14 out of 144 (9.7%) seropositive subjects were hospitalized for community-acquired bacterial pneumonia, compared with six out of 289 (2.1%) seronegative subjects. The cumulative yearly incidence of bacterial pneumonia was 97 out of 1000 for seropositives and 21 out of 1000 for seronegatives (risk ratio = 4.7, P < 0.001). Eleven out of 14 (78.6%) cases among the seropositive patients were due to either Streptococcus pneumoniae or Hemophilus influenzae. Two out of 14 (14.3%) cases among the seropositives were fatal. Stratifying by level of intravenous drug use indicated that even among subjects not reporting active intravenous drug use at study entry, eight out of 82 (9.8%) seropositives compared with three out of 211 (1.4%) seronegatives were hospitalized for bacterial pneumonia over the study period (risk ratio = 6.9, P < 0.01). This study shows a markedly increased incidence of bacterial pneumonia associated with HIV-infection in IVDUs without AIDS. The predominance of S. pneumoniae and H. influenzae suggests that interventions such as immunization of HIV-seropositive IVDUs, antibiotic prophylaxis, or the administration of immunoglobulins, should be considered for further study.