title: Phenotypic and genotypic characteristics of drug resistance in Mycobacterium tuberculosis isolates from pediatric population of Chennai, India.
abstract: OBJECTIVE
  Multidrug-resistant TB (MDR-TB) has been reported in almost all parts of the world. Childhood TB is accorded low priority by national TB control programs. Probable reasons include diagnostic difficulties, limited resources, misplaced faith in BCG and lack of data on treatment. Good data on the burden of all forms of TB among children in India are not available.
  
  
  OBJECTIVE
  To study the drug sensitivity pattern of tuberculosis in children aged from 3 months to 18 years and the outcome of drug-resistant tuberculosis by BACTEC culture system and PCR-based DNA sequencing technique.
  
  
  METHODS
  This is a retrospective study. One hundred and fifty-nine clinical specimens were processed for Ziehl-Neelsen stain, Mycobacterial culture by BACTEC method, phenotypic DST for first-line drugs for Mycobacterium tuberculosis (M. tuberculosis) isolates and PCR-based DNA sequencing was performed for the M. tuberculosis isolates targeting rpoB, katG, inhA, oxyR-ahpC, rpsL, rrs and pncA.
  
  
  CONCLUSIONS
  Out of the 159 Mycobacterial cultures performed during the study period, 17 clinical specimens (10.7%) were culture positive for M. tuberculosis. Among the 17 M. tuberculosis isolates, 2 were multidrug-resistant TB. PCR-based DNA sequencing revealed the presence of many novel mutations targeting katG, inhA, oxyR-ahpC and pncA and the most commonly reported mutation Ser531Leu in the rpoB gene. This study underlines the urgent need to take efforts to develop methods for rapid detection and drug susceptibility of tubercle bacilli in the pediatric population.
authors.affiliation: L & T Microbiology Research Centre, Vision Research Foundation, New No: 41, Old No: 18, College Road, Chennai, India.
authors.forename: K Lily
authors.initials: KL
authors.lastname: Therese
authors.forename: R
authors.initials: R
authors.lastname: Gayathri
authors.forename: S
authors.initials: S
authors.lastname: Balasubramanian
authors.forename: S
authors.initials: S
authors.lastname: Natrajan
authors.forename: H N
authors.initials: HN
authors.lastname: Madhavan
mesh_terms: D000293:Adolescent; D000995:Antitubercular Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D007194:India; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D017422:Sequence Analysis, DNA; D014376:Tuberculosis / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D004269:DNA, Bacterial