title: [In vitro activities of benzoxazinorifamycin KRM-1648 against Mycobacterium tuberculosis].
abstract: 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.
authors.affiliation: Department of Microbiology and Immunology, Shimane Medical University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Tomioka
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: S
authors.initials: S
authors.lastname: Kawahara
authors.forename: T
authors.initials: T
authors.lastname: Hidaka
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D017828:Rifabutin / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology; D012294:Rifamycins / Q000494:pharmacology*
chemical_list: D000904:Antibiotics, Antitubercular; D012294:Rifamycins; C068980:KRM 1648; D017828:Rifabutin; D012293:Rifampin