title: Evaluation of the GenoType MTBDRplus assay for detection of rifampicin- and isoniazid-resistant Mycobacterium tuberculosis isolates in central Ethiopia.
abstract: Multidrug-resistant tuberculosis (MDR-TB) is growing globally and becoming a major challenge for national TB control programs. Therefore, rapid identification of MDR strains of Mycobacterium tuberculosis and monitoring their transmission could contribute significantly to the control of TB. The GenoType MTBDRplus assay has been recommended by the World Health Organization to identify rifampicin (RIF)- and isoniazid (INH)-resistant M. tuberculosis isolates. This study was carried out to evaluate the performance of the GenoType MTBDRplus assay for the detection of RIF- and INH-resistant M. tuberculosis isolates in central Ethiopia.
  
  
  
  A total of 279 M. tuberculosis strains isolated from active TB cases in central Ethiopia were evaluated for their drug sensitivity by the conventional drug-susceptibility test (DST) and compared with data derived from the GenoType MTBDRplus assay. The DST served as the gold standard for evaluating the GenoType MTBDRplus assay.
  
  
  
  The sensitivity and specificity of the GenoType MTBDRplus assay for the detection of RIF-resistant M. tuberculosis isolates were 80.0% and 99.6%, respectively. Its sensitivity and specificity for the detection of INH-resistant M. tuberculosis isolates were 82.7% and 99.6%, respectively, whereas they were 75.0% and 100%, respectively, for the detection of MDR M. tuberculosis strains. The concordances of the GenoType MTBDRplus assay and the conventional DST for the detection of RIF and INH susceptibility were 80% (8/10) and 86.2% (25/29), respectively. Furthermore, the concordance of the two tests for the detection of MDR M. tuberculosis strains was 75%. Specific mutations were detected in 55.6% (5/9) of the RIF-resistant isolates, with the highest mutation rate (33.3%) for the rpoB gene (Codon S531L). For INH-resistant isolates, the highest mutation rate (88.8%) related to a katG mutation (Codon S315T1).
  
  
  
  The findings of this study revealed that the GenoType MTBDRplus assay has high sensitivity and specificity for the detection of RIF and INH resistance. These preliminary data support the notion that the assay should be considered as an alternative to the DST for the characterization of MDR in M. tuberculosis isolates and the control of TB.
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia; Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia; Department of Biology, College of Natural Science and Computational Science, Hawassa University, Hawassa, Ethiopia. Electronic address: zufanw2006@yahoo.com.
authors.forename: Zufan
authors.initials: Z
authors.lastname: Bedewi Omer
authors.affiliation: Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Yalemtsehay
authors.initials: Y
authors.lastname: Mekonnen
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Adane
authors.initials: A
authors.lastname: Worku
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Aboma
authors.initials: A
authors.lastname: Zewde
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Girmay
authors.initials: G
authors.lastname: Medhin
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Temesgen
authors.initials: T
authors.lastname: Mohammed
authors.affiliation: J. Craig Venter Institute, Rockville, MD, United States.
authors.forename: Rembert
authors.initials: R
authors.lastname: Pieper
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Gobena
authors.initials: G
authors.lastname: Ameni
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D005002:Ethiopia; D060005:Genotyping Techniques / Q000379:methods*; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D012293:Rifampin / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid; D012293:Rifampin
keywords: Drug-resistant tuberculosis; Gene mutation; GenoType MTBDRplus assay