Diagnostic Accuracy of GeneXpert MTB/RIF Assay in Comparison to Conventional Drug Susceptibility Testing Method for the Diagnosis of Multidrug-Resistant Tuberculosis

PLoS One. 2017 Jan 12;12(1):e0169798. doi: 10.1371/journal.pone.0169798. eCollection 2017.

Abstract

Xpert MTB/RIF assay is regarded as a great achievement of modern medicine for the rapid diagnosis of multidrug-resistant tuberculosis (MDR-TB). The main purpose of this study was to determine the performance of Xpert MTB/RIF assay compared to conventional drug susceptibility testing (DST) method for the diagnosis of MDR-TB. A comparative cross sectional study was carried out at German-Nepal Tuberculosis Project, Kathmandu, Nepal, from April 2014 to September 2014. A total of 88 culture positive clinical samples (83 pulmonary and 5 extra-pulmonary) received during the study period were analyzed for detection of multidrug-resistant tuberculosis by both GeneXpert MTB/RIF assay and conventional DST method. McNemar chi square test was used to compare the performance of Xpert with that of DST method. A p-value of less than 0.05 was considered as statistically significant. Of total 88 culture positive samples, one was reported as invalid while 2 were found to contain nontuberculous Mycobacteria (NTM). Among remaining 85 Mycobacterium tuberculosis culture positive samples, 69 were found to be MDR-TB positive by both methods. The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of GeneXpert MTB/RIF assay were found to be 98.6%, 100%, 100% and 93.8% respectively. Statistically, there was no significant difference between the diagnostic performance of Xpert and conventional DST method for detection of MDR-TB. GeneXpert MTB/RIF assay was found to be highly sensitive, specific and comparable to gold standard conventional DST method for the diagnosis of MDR-TB.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Drug Resistance, Multiple, Bacterial*
  • Female
  • Humans
  • Male
  • Microbial Sensitivity Tests / methods
  • Middle Aged
  • Mycobacterium tuberculosis* / growth & development
  • Mycobacterium tuberculosis* / isolation & purification
  • Nepal
  • Tuberculosis, Multidrug-Resistant* / diagnosis
  • Tuberculosis, Multidrug-Resistant* / microbiology

Grants and funding

This study was funded by Nepal Health Research Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Mark Formulations Pvt. Ltd. provided support in the form of salaries for author PP, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.