Dr. Mark Pierce
A Vanderbilt University Medical Center researcher has found that a certain antibiotic treatment can help AIDS patients live longer by reducing the incidence of Mycobacterium avium complex (MAC) infection.
Dr. Mark A. Pierce, assistant professor of Medicine, is the lead investigator of a study published in the Aug. 8 issue of The New England Journal of Medicine that shows clarithromycin (Biaxin) prolongs life by lowering the incidence of (MAC) infection in patients with advanced HIV infection.
Pierce said the data show the prophylactic administration of the macrolide antibiotic clarithromycin prevents (MAC) infection and reduces patient mortality.
"This study convincingly shows clarithromycin helps prevent infection in AIDS patients and, in doing so, helps prolong life and improve the patient's quality of life. Patients with advanced AIDS who are severely immunocompromised are at high risk for the onset of opportunistic infections such as disseminated MAC.
"When used as a preventive agent, clarithromycin reduces the risk of disseminated MAC. More importantly, the study has shown that the prophylactic use of clarithromycin extends the lives of patients with advanced AIDS," Pierce said.
Disseminated infection with (MAC) complex is the most common systemic bacterial infection in advanced stages of AIDS – occurring in up to 40 percent of patients – and its incidence appears to be increasing.
The article presents data from a placebo-controlled, double-blind, multi-center study of clarithromycin in AIDS patients in the United States and Europe. The study was designed to assess the ability of clarithromycin to prevent (MAC) infection and the effect of clarithromycin on overall survival of patients.
In the study, a total of 667 patients were given either clarithromycin or placebo. The group receiving clarithromycin was followed for an average of 427 days, while the placebo group was followed for an average of 402 days. During treatment and follow up, only 6 percent of patients in the group receiving clarithromycin developed MAC infections compared to 16 percent in the group receiving placebo. This represents a 69 percent reduction rate in the risk of developing disseminated MAC.
During the follow-up period, 107 deaths (32 percent) were reported in the clarithromycin group, 26 percent lower than the 137 deaths (41 percent) in the placebo group. The overall mortality rate among the patients testing positive for MAC was more than double the rate among patients testing negative for MAC. However, mortality rates among MAC patients remained lower in the clarithromycin group than in the placebo group.
According to the NEJM article, these data suggest that prophylaxis with clarithromycin for patients with advanced AIDS can reduce the occurrence of disseminated infection with MAC. Regarding whether MAC prophylaxis or waiting to treat the onset of disseminated MAC is more effective, the data show that even with active surveillance and treatment in the placebo group, the clarithromycin prophylaxis group still had a markedly better outcome.
Additionally, prophylaxis with clarithromycin may reduce the rate of hospitalization, reduce certain complications of HIV infection (such as pneumonia and giardiasis), and prolong survival in patients with AIDS. Pierce's group says these findings may be due either to the direct effect of clarithromycin or its ability to improve general health by preventing disseminated MAC.
Resistance is a concern with monotherapy in the treatment of AIDS, and is an important issue in MAC prophylaxis, according to the study. Nineteen of 333 patients in the group receiving clarithromycin developed MAC infections; with 11 developing resistance to clarithromycin. Despite the resistance to clarithromycin that developed in these 11 patients, mortality was still lower in the clarithromycin group than in the placebo group.
This study shows that clarithromycin is well tolerated in patients with advanced AIDS. The clarithromycin recipients were no more likely to have severe adverse events or to withdraw from the study than placebo recipients.
Currently, clarithromycin is the only drug approved by the U.S. Food and Drug Administration for both treatment and prophylaxis of MAC infection.
The research was supported by Abbott Laboratories.