Antimicrobial activity of new quinolones against Mycobacterium avium and Mycobacterium intracellulare determined by the dilution methods using 7H11 agar and Ogawa egg media

Abstract

Various new quinolones were measured for their in vitro antimicrobial activities against Mycobacterium avium and M. intracellulare by the two-fold dilution methods using two types of media, 7H11 agar medium and 1% Ogawa egg medium. The MIC90s of test quinolones determined on 7H11 agar medium and Ogawa egg medium were as follows. M. avium (20 strains): ofloxacin (OFLX), 50 and 50 micrograms/ml; ciprofloxacin (CPFX), 12.5 and 25 micrograms/ml; sparfloxacin (SPFX), 6.25 and 12.5 micrograms/ml; fleroxacin (FLRX), 50 and 50 micrograms/ml; Y-26611, 100 and 100 micrograms/ml; OPC-17116, 12.5 and 50 micrograms/ml, for 7H11 agar and Ogawa egg medium, respectively. M. intracellulare (20 strains): OFLX, 50 and 50 micrograms/ml; CPFX, 25 and 25 micrograms/ml; SPFX, 12.5 and 12.5 micrograms/ml; FLRX, 50 and 50 micrograms/ml; Y-26611, > 100 and > 100 micrograms/ml; OPC-17116, 12.5 and > 100 micrograms/ml, for 7H11 agar and Ogawa egg medium, respectively. Thus, the MIC values determined by the 7H11 agar medium were comparable to those by the 1% Ogawa egg medium, except for OPC-17116. Moreover, from the above MIC values, it can be regarded that the potencies of in vitro antimicrobial activity of test quinolones against M. avium are in the order of SPFX > CPFX > or = OPC-17116 > or = OFLX > or = FLRX > Y-26611 and those against M. intracellulare are in the order of SPFX > OPC-17116 not equal to CPFX > OFLX = FLRX > Y-26611. There was found the tendency that M. avium has somewhat higher susceptibility to these quinolones as compared to M. intracellulare.