Efficacy of azithromycin in prevention of Pneumocystis carinii pneumonia: a randomised trial Original Research Article

Background Azithromycin in combination with sulphonamides is active against Pneumocystis carinii pneumonia (PCP) in animals. We assessed the clinical efficacy of azithromycin for PCP prophylaxis in human beings. Methods We identified HV-1-infected patients with PCP during a prospective randomised trial comparing azithromycin, rifabutin, and the two drugs in combination for prevention of disseminated Mycobacterim avium infection. Patients had CD4-cell counts less than 100/ μL at entry and received PCP prophylaxis according to the standard practice of their clinician. Analysis was by intention to treat. Findings Patients receiving azithromycin, either alone (n=233) or in combination with rifabutin (n=224), had a 45% bwer risk of developing PCP than those receiving rifabutin alone (n=236; p=0·008). Compared with rifabutin alone, hazard ratio for azithromycin was 0·54 (95% CI 0·32–0·94), for azithromycin plus rifabutin was 0·55 (0·32–0·94), and for regimens containing azithromycin was 0·55 (0·35–0·86). The most common side-effects involved the gastrointestinal tract with dose-limiting toxicities, and were mainly seen in patients receiving combination therapy. Interpretation Azithromycin as prophylaxis for M avium complex disease provides additional protection against P carinii over and above that of standard PCP prophylaxis. Use of azithromycin is beneficial only as primary prophylaxis.