title: Mutation profiling for detection of isoniazid resistance in Mycobacterium tuberculosis clinical isolates.
abstract: OBJECTIVE
  Progress in the detection of drug-resistant TB has been underpinned by the development and implementation of new, reliable and rapid diagnostic tools. These rely mostly on the detection of specific mutations conferring resistance to anti-TB drugs. The aim of this study was to search for mutations associated with isoniazid resistance among Mycobacterium tuberculosis clinical isolates.
  
  
  METHODS
  A collection of 150 M. tuberculosis strains, including 50 MDR, 50 isoniazid-monoresistant and 50 pan-susceptible strains, was used. For all the strains, seven structural genes (katG, inhA, ahpC, kasA, ndh, nat and mshA) and two regulatory regions (mabA-inhA promoter and oxyR-ahpC intergenic region) were PCR amplified and sequenced in their entirety.
  
  
  RESULTS
  Sixty-six distinct mutations were detected at all nine loci investigated, accounting for 109 (72.7%) of the strains tested. The number of strains with any mutation among the MDR, isoniazid-monoresistant and pan-susceptible groups was 49 (98%), 37 (74%) and 23 (46%), respectively. Mutations in the katG gene predominated, with 29 different types distributed among 46 (92%) MDR, 31 (62%) isoniazid-monoresistant and 2 (4%) pan-susceptible strains. Twenty-nine and 19 mutations were found exclusively in MDR and isoniazid-monoresistant strains, respectively.
  
  
  CONCLUSIONS
  This study revealed 17 mutations, previously unreported, that might be of potential use as new surrogate markers of isoniazid resistance. Their diagnostic accuracy needs to be confirmed on larger strain samples and from different geographical settings. For isoniazid resistance detection, molecular approaches should still be a complement to rather than a replacement for conventional drug susceptibility testing. This is supported by the lack of mutations in any of the nine genetic loci investigated in 18 isoniazid-resistant strains from this study.
authors: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096 Warsaw, Poland t.jagielski@biol.uw.edu.pl.
authors: Tomasz
authors: T
authors: Jagielski
authors: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096 Warsaw, Poland.
authors: Zofia
authors: Z
authors: Bakuła
authors: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096 Warsaw, Poland.
authors: Katarzyna
authors: K
authors: Roeske
authors: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096 Warsaw, Poland.
authors: Michał
authors: M
authors: Kamiński
authors: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096 Warsaw, Poland.
authors: Agnieszka
authors: A
authors: Napiórkowska
authors: Department of Microbiology, National Tuberculosis and Lung Diseases Research Institute, Płocka 26, 01-138 Warsaw, Poland.
authors: Ewa
authors: E
authors: Augustynowicz-Kopeć
authors: Department of Microbiology, National Tuberculosis and Lung Diseases Research Institute, Płocka 26, 01-138 Warsaw, Poland.
authors: Zofia
authors: Z
authors: Zwolska
authors: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096 Warsaw, Poland.
authors: Jacek
authors: J
authors: Bielecki
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D005260:Female; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012045:Regulatory Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid