[In vitro activities of benzoxazinorifamycin KRM-1648 against Mycobacterium tuberculosis].
In vitro antimicrobial activities of the benzoxazinorifamycin derivative KRM-1648 (KRM) against 50 strains of Mycobacterium tuberculosis isolated from patients with mainly intractable pulmonary tuberculosis were studied. MIC90 values of KRM, rifabutin (RBT) and rifampicin (RFP) for RFP-sensitive strains (27 strains; defined as those with MICRFP values of < 1.56 micrograms/ml) were 0.013, 0.1 and 0.4 micrograms/ml, respectively, when determined by the agar dilution method using 7H11 medium. MIC90 values of KRM, RBT, and RFP for RFP-resistant strains (23 strains; defined as those having MICRFP values of > or = 1.56 micrograms/ml) were 100, 12.5 and > 100 micrograms/ml, respectively. MICs of KRM against 50 clinical isolates of M. tuberculosis distributed over a much lower range than those of RFP. KRM showed more potent antimicrobial activity than RBT against the organisms with low MIC values (< or = 1.56 micrograms/ml), while it was not so active as RBT against the organisms with high MIC values (> or = 3.13 micrograms/ml). Cross-resistance between KRM and RFP or RBT was observed for M. tuberculosis.
Sato
K
K
Department of Microbiology and Immunology, Shimane Medical University, Japan.
Tomioka
H
H
Saito
H
H
Kawahara
S
S
Hidaka
T
T
D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D017828:Rifabutin / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology; D012294:Rifamycins / Q000494:pharmacology*
D000904:Antibiotics, Antitubercular; D012294:Rifamycins; C068980:KRM 1648; D017828:Rifabutin; D012293:Rifampin