Roxithromycin alone and in combination with either ethambutol or levofloxacin for disseminated Mycobacterium avium infections in beige mice.

Roxithromycin alone reduced the level of bacteremia caused by Mycobacterium avium complex liver and splenic infection (in CFU per gram) of beige mice and mortality compared with untreated controls (P < 0.05). Roxithromycin plus ethambutol resulted in a significant reduction in the number of bacteria in splenic tissue compared with those in control splenic tissues of mice and mice treated with roxithromycin alone and ethambutol alone. Roxithromycin plus levofloxacin was not better than roxithromycin alone. Roxithromycin has in vivo activity against M. avium complex strains, and pilot studies with humans may be considered.