title: M. tuberculosis Central Asian Strain 1 MDR isolates have more mutations in rpoB and katG genes compared with other genotypes.
abstract: Pakistan ranks eighth globally among TB burden countries, with a MDR rate of 2-5%. The most prevalent MTB genotype is Central Asian Strain1 (CAS1) followed by the Beijing genogroup. We investigated common mutations in multidrug resistance encoding genes rpoB, katG and inhA of CAS1 and Beijing strains using DNA sequencing and fluorescent resonance energy transfer (FRET) probe based real-time PCR methods. 30 CAS1, 12 Beijing and 20 unclustered spoligotypes, and 10 susceptible MTB strains were tested. The most common mutations in the rpoB gene were at codons 531 (60%), 526 (23%) and 516 (5%). CAS1 strains had a higher frequency of mutations at codon 526 (p<0.001), with more concurrent mutations (p<0.05) compared with Beijing and orphan types. Mutations at codon 315 of the katG gene were higher in CAS1 than Beijing strains (p=0.052). Only 1/62 MDR strain, which belonged to CAS1, had a mutation in the inhA gene. Sensitivity and specificity of probe based assay was 93% and 100% for rpoB, and 95% and 100% for katG, respectively. The FRET probes method detected 84% and 60% of rpoB and katG mutations and can therefore be used as a rapid method of screening MTB strains including CAS1.
authors.affiliation: Department of Pathology and Microbiology, The Aga Khan University, Karachi, Pakistan.
authors.forename: Asho
authors.initials: A
authors.lastname: Ali
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hasan
authors.forename: Tariq
authors.initials: T
authors.lastname: Moatter
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Tanveer
authors.forename: Rumina
authors.initials: R
authors.lastname: Hasan
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002374:Catalase / Q000235:genetics*; D015342:DNA Probes; D012321:DNA-Directed RNA Polymerases; D024901:Drug Resistance, Multiple, Bacterial; D031541:Fluorescence Resonance Energy Transfer; D005838:Genotype; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D010154:Pakistan; D016133:Polymerase Chain Reaction; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D015342:DNA Probes; C505805:rpoB protein, Mycobacterium tuberculosis; D002374:Catalase; C480353:katG protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D007538:Isoniazid; D012293:Rifampin