Journal of Antimicrobial Chemotherapy (1995) 36, 641-646
© 1995 The British Society for Antimicrobial Chemotherapy
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Efficacy of azithromycin and rifabutin in preventing infection by Mycobacterium avium complex in beige mice
aKuzell Institute for Arthritis and Infectious Diseases California Pacific Medical Center Research Institute, San Francisco, California, 94115 bDepartment of Pathology and Laboratory Medicine Children's Hospital, Los Angeles, Los Angeles, California 90027, USA
returned 12 February 1995; accepted 18 May 1995
We investigated the potential of the azalide, azithromycin, and rifabutin in preventing disseminated infection due to Mycobacterium avium complex (MAC) in beige mice. Azithromycin 200 mg/kg, rifabutin (30 mg/kg or 60 mg/kg) were administered by gavage 6 days before mice were challenged orally with 108cfu MAC and daily for 10 days thereafter during which time the mice were again challenged with the same inoculum on alternate days (days +1, +3, +5, +7, and +9). Sixty-four days later, the presence of bacteria in the blood and the number of viable bacteria in liver, spleen and appendix were estimated. Treatment with azithromycin and 60 mg/kg/day rifabutin but not 30 mg/kg/day, significantly decreased the incidence of bacteraemia and the number of bacteria in the appendix. The administration of azithromycin resulted in significantly fewer MAC in the liver and spleen but not in the appendix whereas the converse was true of 60 mg/kg rifabutin. Our results indicate that both azithromycin and rifabutin can prevent MAC disseminated infection, but that the azalide is more effective than the rifamycin in reducing the burden of infection.