Intracellular activity of azithromycin against Mycobacterium avium complex in human macrophages

In the concentration range examined (0.5-16 micrograms/ml) the azalide antibiotic azithromycin (CAS 83905-01-5, Zithromax) inhibited the growth of mycobacteria in macrophages over 7 days. The higher concentrations of azithromycin, 8 and 16 micrograms/ml, reduced the number of phagocytized bacteria in macrophages by at least 1 log unit within 4 days. The system used, macrophages from healthy volunteers, is suitable for testing the intracellular activity of drugs against the Mycobacterium avium complex.