Bactericidal action of oral ampicillin/sulbactam against Mycobacterium leprae

We reported previously that an injectable form of ampicillin/sulbactam, Una syn, was bactericidal to Mycobacterium leprae multiplying in mouse foot pad s, In this study, we examined the effect of an orally active form of ampici llin/sulbactam, Sultamicillin, on the growth of M. leprae in mice. Three co ncentrations of the drug, mixed with the feed, were administered from the s tart until the mice were killed at 6 months; 0.01% of the drug inhibited ba cterial growth by 54%, 0.10% by 74% and 0.20% by 93%. To test whether oral ampicillin/sulbactam was bactericidal, 0.50% of the drug, mixed with the fe ed, was administered to experimentally infected mice for 3 months during th e logarithmic phase of bacterial growth, and then discontinued; multiplicat ion of the bacilli was monitored monthly for the next 8 months. The results showed that orally active ampicillin/sulbactam is bactericidal to M. lepra e.