[A study of beta-lactamase activity of mycobacteria and clinical trial of penicillin/beta-lactamase inhibitor combinations in the treatment of drug-resistant Mycobacterium tuberculosis].

: Beta-lactamase activity was determined using a nitrocefin disc method on 34 Mycobacterium tuberculosis (M. tuberculosis) strains and 13 nontuberculous mycobacteria strains. In the 34 M. tuberculosis strains, 23 strains showed beta-lactamase activity. In 10 Mycobacterium avium complex strains, no beta-lactamase activity was detected. In the Mycobacterium chelonae strains, all three strains examined showed strong beta-lactamase activity. No correlation was found between beta-lactamase activity and resistance to anti-tuberculous chemotherapeutic agents. Four patients who were persistently positive for multi-drug-resistant M. tuberculosis (MDR-TB) on sputum and positive in beta-lactamase activity, were treated with penicillin/beta-lactamase inhibitor combinations. In two cases, the trials were discontinued because of diarrhea; the trials were continued in the remaining two for four months, but the MDR-TB was positive during the course of the therapy. Effectiveness of the therapy with penicillin/beta-lactamase inhibitor combinations against M. tuberculosis was obscure, although many of M. tuberculosis examined showed beta-lactamase activity.