title: Detection of rifampin resistance among isolates of Mycobacterium tuberculosis from Mozambique.
abstract: Rifampin resistance in respiratory isolates of Mycobacterium tuberculosis from Mozambique was detected by screening for point mutations using polymerase chain reaction (PCR) and DNA sequence analysis. The target template was a 350-bp fragment of rpoB encoding the beta-subunit of the RNA polymerase. Of the 66 strains studied, 38 were rifampin resistant by susceptibility testing with the radiometric method, 3 were intermediately resistant, and 25 were susceptible to rifampin. In 39 of the 41 rifampin-resistant strains, base-substitutions in the rpoB fragment were detected, and a total of 13 distinct mutations affecting 6 amino acids were observed. One of these mutations (His-->Thr in amino acid 526) was not previously described. The isolates were also investigated by restriction fragment length polymorphism (RFLP) analysis using the insertion element IS6110 as a hybridization probe. A total of 47 RFLP patterns were identified, with up to 9 isolates having the same RFLP pattern. Strains with the same RFLP pattern harbored different mutations in rpoB, suggesting that acquisition of rifampin resistance followed the spread of a rifampin-susceptible clone. The data showed that rifampin resistance can be detected with a high sensitivity by DNA sequence analysis of this fragment of rpoB. However, a few strains with rifampin resistance due to factors other than base substitutions in rpoB could be missed.
authors.affiliation: Department of Bacteriology, National Institute of Public Health, Oslo, Norway.
authors.forename: D A
authors.initials: DA
authors.lastname: Caugant
authors.forename: P
authors.initials: P
authors.lastname: Sandven
authors.forename: J
authors.initials: J
authors.lastname: Eng
authors.forename: J T
authors.initials: JT
authors.lastname: Jeque
authors.forename: T
authors.initials: T
authors.lastname: Tønjum
mesh_terms: D000595:Amino Acid Sequence; D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009073:Mozambique; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012293:Rifampin / Q000494:pharmacology*; D014397:Tuberculosis, Pulmonary / Q000382:microbiology*
chemical_list: D000904:Antibiotics, Antitubercular; D004269:DNA, Bacterial; D012293:Rifampin