Possible effectiveness of clarithromycin and rifabutin for cryptosporidiosis chemoprophylaxis in HIV disease

Context. - Cryptosporidium parvum infection, a common cause of diarrhea in persons infected with the human immunodeficiency virus (HIV), is difficult to treat or prevent. Objective. - To evaluate relative rates of cryptosporidiosis in HIV-infected patients who were either receiving or not receiving chemoprophylaxis or treatment for Mycobacterium avium complex. Design. - Analysis of prospectively collected data from HIV-infected patients' visits to their physicians since 1992. Setting. - Ten (8 private, 2 publicly funded) HIV clinics in 9 US cities. Patients. - A total of 1019 HIV- infected patients with CD4⁺ cell counts less than 0.075 x 10⁹/L. Main Outcome Measures. - Incidence of clinical cryptosporidiosis during treatment with clarithromycin, rifabutin, and azithromycin. Results. - Five of the 312 patients reportedly taking clarithromycin developed cryptosporidiosis vs 30 of the 707 patients not taking clarithromycin (relative hazard [RH], 0.25 [95% confidence interval (Cl), 0.10-0.67]; P=.004). Two of the 214 patients taking rifabutin developed cryptosporidiosis vs 33 of the 805 not taking rifabutin (RH, 0.15 [95% Cl, 0.04-0.62]; P=.01). Prophylactic efficacy of either drug was 75% or greater. No protective effect was seen in the 54 patients reportedly taking azithromycin (RH, 1.48 [95% Cl, 0.44-5.04]; P=.46). Conclusions. - Clarithromycin and rifabutin were highly protective against development of cryptosporidiosis in immune-suppressed HIV-infected persons in this analysis; further study is warranted.