title: Sequence analysis of rpoB mutations in rifampin-resistant clinical Mycobacterium tuberculosis isolates from Turkey.
abstract: Drug-resistant tuberculosis is a serious problem throughout the world. Resistance to Rifampicin (RIF) is mainly caused by the mutations in the rpoB gene coding the beta-subunit of RNA polymerase. In this study, we aimed to detect the distribution of rpoB gene mutations in 80 RIF-resistant clinical Mycobacterium tuberculosis (MTB) isolates from Turkey. The rpoB gene was amplified by PCR and mutations leading to RIF resistance were determined by automated sequence analysis. A total of 72 of the 80 isolates (90%) were found to carry mutations in the amplified region, whereas eight isolates (10%) carried no mutations. Overall, 24 different missense mutations affecting 14 codons, and two deletion mutants were identified. Nine new mutations, six in the hot-spot region and three outside this region, were found. The codon numbers of the most frequently encountered mutations were 531 (51.4%), 526 (18.1%), 516 (13.9%), and 513 (12.5%). As a result, 90% of the RIF-resistant MTB isolates from the Turkish patients were found to carry a mutation in the rpoB gene, Ser531Leu being the most frequent one. Although molecular methods identify mutations leading to RIF resistance very quickly, results of the antimycobacterial susceptibility tests must be taken into consideration for the patients carrying no mutations in this region.
authors.affiliation: Ankara University, Faculty of Medicine, Department of Pediatric Molecular Pathology and Genetics, Ankara, Turkey. ckarahan@medicine.ankara.edu.tr
authors.forename: Zeynep Ceren
authors.initials: ZC
authors.lastname: Karahan
authors.forename: Figen
authors.initials: F
authors.lastname: Atalay
authors.forename: Meltem
authors.initials: M
authors.lastname: Uzun
authors.forename: Zayre
authors.initials: Z
authors.lastname: Erturan
authors.forename: Melike
authors.initials: M
authors.lastname: Atasever
authors.forename: Nejat
authors.initials: N
authors.lastname: Akar
mesh_terms: D000328:Adult; D000368:Aged; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D012293:Rifampin / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology / Q000208:ethnology / Q000382:microbiology*; D014421:Turkey / Q000453:epidemiology
chemical_list: D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D012293:Rifampin