Synergistic anti-pneumocystis carinii effects of erythromycin and sulfisoxazole

Pneumocystis carinii pneumonia (PCP) is an opportunistic infection that often occurs in patients with AIDS, and causes high morbidity (illness) and mortality. A number of drug therapies have been developed that are effective in preventing PCP in AIDS patients. Some use a combination of drugs that have little or no effect alone, but are highly effective when administered together, thus providing a synergistic effect. This study examined a combination of erythromycin and sulfisoxazole treatment to prevent PCP in an animal model. Rats were given a drug to suppress their immune systems and increase their vulnerability to the development of PCP. The rats were grouped and either given no drug, azithromycin, clarithromycin, erythromycin, sulfisoxazole, or a combination of erythromycin and sulfisoxazole. None of the drugs alone had much effect in preventing PCP; 80 to 100 percent of the rats in each group developed PCP infection. When erythromycin and sulfisoxazole were given in combination, only 10 percent of the rats developed PCP. This drug combination has been safely used in humans for other diseases for a number of years. Drug models using animals have worked well for PCP studies. The results from this study indicate that the combination therapy of erythromycin and sulfisoxazole should be examined as a means of preventing PCP in patients with AIDS. (Consumer Summary produced by Reliance Medical Information, Inc.)