title: In-vitro activity of rifabutin against rifampicin-resistant Mycobacterium tuberculosis isolates with known rpoB mutations.
abstract: The relationship between resistance to rifampicin and rifabutin and genetic alterations in the rpoB gene of 41 rifampicin-resistant isolates of Mycobacterium tuberculosis was evaluated. Although 35 isolates with rifampicin MICs > or = 32 mg/L were also rifabutin-resistant, six isolates with rifampicin MICs of 2-16 mg/L were susceptible to rifabutin (MIC < or = 0.5 mg/L). Mutations Asp516Val, Asp516Tyr, Leu533Pro and the double mutation Met515Ile and Leu533Pro influenced susceptibility to rifampicin, but not to rifabutin. All mutations at codons 531 and 526, except one isolate with a His526Cys mutation, correlated with resistance to both compounds.
authors.affiliation: Microbiology and Clinical Microbiology, Ege University Medical Faculty, Izmir, Turkey. cengizc@hotmail.com
authors.forename: C
authors.initials: C
authors.lastname: Cavusoglu
authors.forename: Y
authors.initials: Y
authors.lastname: Karaca-Derici
authors.forename: A
authors.initials: A
authors.lastname: Bilgic
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics; D017828:Rifabutin / Q000494:pharmacology*; D012293:Rifampin / Q000494:pharmacology*; D017422:Sequence Analysis, DNA
chemical_list: D000904:Antibiotics, Antitubercular; D017828:Rifabutin; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D012293:Rifampin