Effect of chronic systemic use of trimethoprim-sulfamethoxazole in the conjunctival bacterial flora of patients with HIV infection.

Abstract

To investigate the effect of orally administered trimethoprim-sulfamethoxazole (TMP-SMZ) on the prevalence, species distribution, and resistance of the conjunctival bacterial flora in adults with human immunodeficiency virus (HIV) infection. Cross-sectional study, with clinical and experimental laboratory investigation. Samples from the inferior conjunctival fornix were collected and submitted for culture to evaluate aerobic flora. Sixty samples were collected. Negative cultures were found in 17 (56.7%) eyes of the TMP-SMZ group and in 10 (33%) of the control group (P = .036). All Staphylococcus species isolates in the TMP-SMZ group were resistant to the drug, whereas 50% of the control group presented this finding (P = .025). In the study group, all bacteria were resistant to TMP-SMZ, compared with only 47% of the microorganisms in the control group. Orally administered TMP-SMZ in patients with HIV infection seems to exert a selection pressure in the microorganisms present on the conjunctiva.