title: Characteristics of pncA mutations in multidrug-resistant tuberculosis in Taiwan.
abstract: BACKGROUND
  Pyrazinamide (PZA) is an important first-line drug in multidrug-resistant tuberculosis (MDRTB) treatment. However, the unreliable results obtained from traditional susceptibility testing limits its usefulness in clinical settings. The detection of pncA gene mutations is a potential surrogate of PZA susceptibility testing, especially in MDRTB isolates. The impact of genotypes of M. tuberculosis in pncA gene mutations also remains to be clarified.
  
  
  METHODS
  MDRTB isolates were collected from six hospitals in Taiwan from January 2007 to December 2009. pncA gene sequencing, pyrazinamidase activity testing, and spoligotyping were performed on all of the isolates. PZA susceptibility was determined by the BACTEC MGIT 960 PZA method. The sensitivity and specificity of pncA gene analysis were estimated based on the results of PZA susceptibility testing.
  
  
  RESULTS
  A total of 66 MDRTB isolates, including 37 Beijing and 29 non-Beijing strains, were included for analysis. Among these isolates, 36 (54.5%) were PZA-resistant and 30 (45.5%) were PZA-susceptible. The PZA-resistant isolates were more likely to have concomitant resistance to ethambutol and streptomycin. Thirty-seven mutation types out of 30 isolates were identified in the pncA gene, and most of them were point mutations. The sensitivities of pncA gene sequencing for PZA susceptibility in overall isolates, Beijing and non-Beijing strains were 80.6%, 76.2%, and 86.7% respectively, and the specificities were 96.7%, 93.8%, and 100% respectively.
  
  
  CONCLUSIONS
  More than half of the MDRTB isolates in this study are PZA-resistant. Analysis of pncA gene mutations helped to identify PZA-susceptible MDRTB isolates, especially in non-Beijing strains.
authors.affiliation: Department of Chest Medicine, Taipei Veterans General Hospital, Shih-Pai Rd,, Taipei 112, Taiwan, ROC.
authors.forename: Yu-Chi
authors.initials: YC
authors.lastname: Chiu
authors.forename: Shiang-Fen
authors.initials: SF
authors.lastname: Huang
authors.forename: Kwok-Woon
authors.initials: KW
authors.lastname: Yu
authors.forename: Yu-Chin
authors.initials: YC
authors.lastname: Lee
authors.forename: Jia-Yih
authors.initials: JY
authors.lastname: Feng
authors.forename: Wei-Juin
authors.initials: WJ
authors.lastname: Su
mesh_terms: D000328:Adult; D000368:Aged; D000581:Amidohydrolases / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D058889:Molecular Typing; D020125:Mutation, Missense; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D013624:Taiwan; D018088:Tuberculosis, Multidrug-Resistant / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D000581:Amidohydrolases; C487496:PncA protein, Mycobacterium tuberculosis; C022490:pyrazinamide deamidase