title: Performance comparison of four methods for detecting multidrug-resistant Mycobacterium tuberculosis strains.
abstract: METHODS
  National Tuberculosis Reference Laboratory, Kuwait.
  
  
  OBJECTIVE
  To compare Genotype MTBDRplus (gMTBDR(+)), INNO-LiPA Rif.TB (INNO-LiPA), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing for detecting rifampicin (RMP) and/or isoniazid (INH) resistance-associated mutations in the rpoB hot-spot region (HSR-rpoB), the katG codon 315 (katG315) and the inhA regulatory region (inhA-RR) among multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates.
  
  
  METHODS
  A total of 82 MDR-TB and 43 pansusceptible M.tuberculosis BACTEC 460-characterised isolates were processed using molecular techniques and the Mycobacterial Growth Indicator Tube (MGIT) 960 system.
  
  
  RESULTS
  All susceptible strains contained wild-type sequences in target genes. RMP resistance was detected in respectively 78, 77 and 79 MDR-TB strains by gMTBDR(+), INNO-LiPA and HSR-rpoB sequencing. Two isolates with Ins514TTC mutation were detected as RMP-resistant by gMTBDR(+) but as RMP-susceptible by INNO-LiPA. One isolate with L533P mutation, detected as RMP-susceptible by gMTBDR(+), was detected as RMP-resistant by INNO-LiPA. Two of three isolates detected as RMP-susceptible by gMTBDR(+), INNO-LiPA, HSR-rpoB sequencing and the MGIT 960 system contained a I572F mutation that is outside HSR-rpoB. INH resistance was detected in respectively 76, 60, 60 and 22 MDR-TB strains by gMTBDR(+), katG315 PCR-RFLP, katG315 sequencing and inhA-RR sequencing.
  
  
  CONCLUSIONS
  Although gMTBDR(+) accurately detected ∼ 88% of MDR-TB strains, some rpoB mutations were either missed or were outside the region of analysis of the gMTBDR(+) assay.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, Kuwait.
authors.forename: N M
authors.initials: NM
authors.lastname: Al-Mutairi
authors.forename: S
authors.initials: S
authors.lastname: Ahmad
authors.forename: E
authors.initials: E
authors.lastname: Mokaddas
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics; D001431:Bacteriological Techniques; D002374:Catalase / Q000235:genetics; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000032:analysis*; D012321:DNA-Directed RNA Polymerases; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D007730:Kuwait; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D010088:Oxidoreductases / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011237:Predictive Value of Tests; D012293:Rifampin / Q000627:therapeutic use; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C505805:rpoB protein, Mycobacterium tuberculosis; D010088:Oxidoreductases; D002374:Catalase; C480353:katG protein, Mycobacterium tuberculosis; C085257:InhA protein, Mycobacterium; D012321:DNA-Directed RNA Polymerases; D007538:Isoniazid; D012293:Rifampin