title: Performance of Genotype MTBDRplus in the Detection of Resistance to Rifampicin and Isoniazid Among Clinical Mycobacteria Isolates in Ilorin, Nigeria.
abstract: BACKGROUND
  Performance of Genotype MTBDRplus assay against Lowenstein Jensen (LJ) proportion method of Drug Susceptibility Testing (DST) in detection of resistance among clinical mycobacteria isolates to rifampicin (RMP) and isoniazid (INH) was evaluated in Ilorin, Nigeria.
  
  
  METHODS
  This retrospective study characterized one hundred mycobacteria isolates from pulmonary TB patients, stored on LJ medium and subcultured unto fresh LJ slants before being genotyped using MTBDRplus assay. DST was performed on the isolates against RMP, INH, Ethambutol and Streptomycin.
  
  
  RESULTS
  Genotype MTBDRplus identified 97% and 3% of the 100 isolates as Mycobacterium tuberculosis Complex (MTBC) and Non-Tuberculous Mycobacteria (NTM) respectively. Fourteen of the isolates, (14%) were resistant to RMP while 86% were sensitive by the genotypic method. Three of these 14 RMP-resistant isolates were NTMs while 11 were MTBC. Twelve (12%) of the 100 isolates were resistant to INH. Three INH-resistant isolates were NTMs, and 9 were MTBC. Phenotypically and genotypically, the 3 NTMs were resistant to RMP and INH and ten of the 97 MTBC strains were RMP-resistant. One RMP-phenotypically-sensitive strain was genotypically resistant to RMP. Six of the MTBC isolates were resistant to both RMP and INH by both methods. Most mutations occurred in the S-531L and S315T1 codons of rpoB and KatG genes of RMP and INH, respectively.
  
  
  CONCLUSIONS
  The high specificity and positive predictive values recorded by MTBDRplus in our study make it suitable for use in the programmatic management of drug-resistant TB in resource-limited settings.
authors.affiliation: Clinical Laboratory Services Department, Institute of Human Virology, Pent House, Main Court, Plot 252, Herbert Macaulay Way, Central Business District, Abuja, Nigeria. anwofor@ihvnigeria.org.
authors.forename: Alfred C
authors.initials: AC
authors.lastname: Nwofor
authors.forename: Amaase
authors.initials: A
authors.lastname: Nyamngee
authors.forename: Charles
authors.initials: C
authors.lastname: Nwabuisi
authors.forename: Mosunmola
authors.initials: M
authors.lastname: Iwakun
authors.forename: Masur
authors.initials: M
authors.lastname: Gidado
authors.forename: Charles
authors.initials: C
authors.lastname: Mensah
authors.forename: Patrick
authors.initials: P
authors.lastname: Dakum
authors.forename: Oladjide O
authors.initials: OO
authors.lastname: Agbede
authors.forename: Nicaise
authors.initials: N
authors.lastname: Ndembi
authors.forename: William A
authors.initials: WA
authors.lastname: Blattner
authors.forename: Alashle G
authors.initials: AG
authors.lastname: Abimiku
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D005838:Genotype; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009159:Mycobacteriaceae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D009549:Nigeria; D012189:Retrospective Studies; D012293:Rifampin / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D007538:Isoniazid; D012293:Rifampin