title: Mutations in rpoB gene of rifampicin resistant clinical isolates of Mycobacterium tuberculosis in Japan.
abstract: In Mycobacterium tuberculosis, involvement of alterations of the RNA polymerase beta subunit in resistance to rifampicin has been described by Telenti et al. To determine if the same correlation could be observed between the mutation of the rpoB gene and clinically isolated M. tuberculosis of the rifampicin-resistant phenotype in Japan, 47 strains of M. tuberculosis of the rifampicin-resistant phenotype, 17 of the rifampicin-susceptible phenotype, and 4 type strains were examined. A 411-base pair (bp) rpoB fragment was amplified by the polymerase chain reaction and subjected to solid phase direct sequencing. By comparing the nucleotides, mutation involving 8 conserved amino acids were identified in 44 of the 47 (93.6%) rifampicin-resistant isolates, but in none of the 17 sensitive isolates and 4 type strains. All mutations found were clustered within a region of 23 amino acids. Thus, similar to the results reported by Telenti et al., substitution of a limited number of highly conserved amino acids encoded by the rpoB gene appears to be the molecular mechanism responsible for resistance to rifampicin in Japanese clinical isolates of M. tuberculosis. Our results suggest that direct DNA sequencing of the rpoB gene may be a reliable method for identifying rifampicin-resistant M. tuberculosis strains among Japanese clinical isolates.
authors.affiliation: Department of Pathology, Osaka Prefectural Institute of Public Health, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.forename: C
authors.initials: C
authors.lastname: Katsukawa
authors.forename: K
authors.initials: K
authors.lastname: Inoue
authors.forename: Y
authors.initials: Y
authors.lastname: Yin
authors.forename: H
authors.initials: H
authors.lastname: Tasaka
authors.forename: N
authors.initials: N
authors.lastname: Ueba
authors.forename: M
authors.initials: M
authors.lastname: Makino
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial; D006801:Humans; D007564:Japan; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D017354:Point Mutation; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D012293:Rifampin