title: Diagnostic Accuracy of GeneXpert MTB/RIF Assay in Comparison to Conventional Drug Susceptibility Testing Method for the Diagnosis of Multidrug-Resistant Tuberculosis.
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.
authors.affiliation: Department of Microbiology, Mark Formulations Pvt. Ltd., Kathmandu, Nepal.
authors.forename: Pratikshya
authors.initials: P
authors.lastname: Pandey
authors.affiliation: Department of Microbiology, Grande International Hospital, Dhapasi, Kathmandu, Nepal.
authors.forename: Narayan Dutt
authors.identifier: http://orcid.org/0000-0002-7577-2633
authors.initials: ND
authors.lastname: Pant
authors.affiliation: Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal.
authors.forename: Komal Raj
authors.initials: KR
authors.lastname: Rijal
authors.affiliation: German Nepal Tuberculosis Project- National Reference Laboratory, Kathmandu, Nepal.
authors.forename: Bhawana
authors.initials: B
authors.lastname: Shrestha
authors.affiliation: Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal.
authors.forename: Sirita
authors.initials: S
authors.lastname: Kattel
authors.affiliation: Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal.
authors.forename: Megha Raj
authors.initials: MR
authors.lastname: Banjara
authors.affiliation: German Nepal Tuberculosis Project- National Reference Laboratory, Kathmandu, Nepal.
authors.forename: Bhagwan
authors.initials: B
authors.lastname: Maharjan
authors.affiliation: Department of Biochemistry, Modern Technical College, Lalitpur, Nepal.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Kc
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000254:growth & development / Q000302:isolation & purification; D009390:Nepal; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis / Q000382:microbiology