Infrequency of pulmonary microbial colonisation prior to respiratory disease in HIV-infected individuals.

To determine whether organisms are present in the HIV-infected lung prior to clinical respiratory disease, a cross-sectional bronchoscopic comparative analysis of 39 asymptomatic HIV-positive subjects and 31 healthy controls with 2-year prospective bronchoscopic monitoring of the HIV study group was performed. Pathological examination of bronchoalveolar lavage (BAL) fluid using standard microbiological techniques was undertaken. Organisms were recovered from similar numbers of HIV-positive and control subjects (7 of 39 and 3 of 31) and comprised predominantly scanty growths of bacteria. Five subjects developed respiratory disease during follow-up. Repeat BAL was performed in 11 asymptomatic HIV-positive patients; no relationship was found between the organisms isolated at the two procedures. The findings suggest that the asymptomatic HIV-positive lung is not a frequent site of either microbial colonisation or subclinical infection. This has implications for the understanding of the pathogenesis of HIV-related pulmonary disease.