title: Mutation in the rpoB gene of the rifampicin resistant M. avium complex strains from Thailand.
abstract: Forms of mutation never before described in the rpoB gene are reported for a sample of 20 rifampicin-resistant Mycobacterium avium Complex (MAC) strains isolated from AIDS patients in Thailand. All strains were analyzed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and polymerase chain reaction-DNA sequencing (PCR-DNA sequencing). Sequence analysis of these strains revealed that only one strain (5%) has missense mutation at Lys-626 (Thr) and the rest of the strains had 15 different silent mutations within a 542 bp region of the rpoB gene. Five strains (25%) had a silent mutation at only one position, 7 (35%) at 2 positions, 7 (35%) at 3 positions, and 1 (5%) at 7 positions. The silent mutation at the Ala-630 codon occurred in the largest proportion of the strains (15 strains, 75%), followed by the Val-581 in 8 strains (40%), Tyr-578 and Thr-600 in 4 strains (20%), and Gly-597 in 3 strains (15%). This investigation demonstrates that mutation in the rpoB gene of MAC strains from Thailand are more varied than previously reported for RIF MAC strains. PCR-SSCP screening clearly separated RIFr strains from rifampicin-susceptible (RIFs) strains.
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Oranuch
authors.initials: O
authors.lastname: Kongpetchsatit
authors.forename: Wanchai
authors.initials: W
authors.lastname: Phatihattakorn
authors.forename: Yuvadee
authors.initials: Y
authors.lastname: Mahakunkijcharoen
authors.forename: Boonchuay
authors.initials: B
authors.lastname: Eampokalarp
authors.forename: Jirakan
authors.initials: J
authors.lastname: Boonyasopun
authors.forename: Pongrama
authors.initials: P
authors.lastname: Ramasoota
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005798:Genes, Bacterial; D006801:Humans; D009154:Mutation; D015269:Mycobacterium avium Complex / Q000235:genetics*; D015270:Mycobacterium avium-intracellulare Infection / Q000235:genetics*; D012293:Rifampin / Q000494:pharmacology*; D013785:Thailand
chemical_list: D000904:Antibiotics, Antitubercular; D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin