IN VITRO AND IN VITRO ACTIVITES OF CEFOXITIN ALONE OR IN COMBINATION WITH ANTITUBERCULOSIS DRUGS AGAINST MYCOBACTERIUM FORTUITUM COMPLEX

Abstract

The comparative in vitro activity of cefoxitin (CFX) alone or in combination with isoniazide (INH), rifampicin (RFP), ethambutol (EB), streptomycin (SM), kanamycin (KM) and minocycline (MINO) against Mycobacterium fortuitum complex was evaluated by agar dilution method. MIC₉₀ of CFX against these organisms was 50μg/ml or higher. A combination of CFX-EB-INH-RFP inhibited 9 of 10 strains of M. fortuitum at 0.8μg/ml. MIC₉₀ of these combination against M. chelonae (subsp. abscessus and subsp. chelonae) were 6.25μg/ml in both cases.
Mice inoculated intravenously with M. fortuitum 18367 were treated with CFX alone or in combination with EB-INH-RFP once daily for 4 weeks, beginning 24 h after challenge. Enhancement of therapeutic effects of these combined drugs to M. fortuitum-infected mice was not shown when compared with CFX alone.