Performance of the G4 Xpert(R) MTB/RIF assay for the detection of Mycobacterium tuberculosis and rifampin resistance: a retrospective case-control study of analytical and clinical samples from high- and low-tuberculosis prevalence settings
Authors
Dharan, Nila J.Blakemore, Robert
Sloutsky, Alexander
Kaur, Devinder
Alexander, Richard C.
Ghajar, Minoo
Musser, Kimberlee A.
Escuyer, Vincent E.
Rowlinson, Marie-Claire
Crowe, Susanne
Laniado-Laborin, Rafael
Valli, Eloise
Nabeta, Pamela
Johnson, Pamela
Alland, David
UMass Chan Affiliations
Department of Medicine, Division of Infectious Diseases and ImmunologyDocument Type
Journal ArticlePublication Date
2016-12-20Keywords
DiagnosticsG4
GeneXpert
Tuberculosis
Xpert
Bacterial Infections and Mycoses
Immunology and Infectious Disease
Infectious Disease
Microbiology
Metadata
Show full item recordAbstract
BACKGROUND: The Xpert(R) MTB/RIF (Xpert) assay is a rapid PCR-based assay for the detection of Mycobacterium tuberculosis complex DNA (MTBc) and mutations associated with rifampin resistance (RIF). An updated version introduced in 2011, the G4 Xpert, included modifications to probe B and updated analytic software. METHODS: An analytical study was performed to assess Xpert detection of mutations associated with rifampin resistance in rifampin-susceptible and -resistant isolates. A clinical study was performed in which specimens from US and non-US persons suspected of tuberculosis (TB) were tested to determine Xpert performance characteristics. All specimens underwent smear microscopy, mycobacterial culture, conventional drug-susceptibility testing and Xpert testing; DNA from isolates with discordant rifampin resistance results was sequenced. RESULTS: Among 191 laboratory-prepared isolates in the analytical study, Xpert sensitivity for detection of rifampin resistance associated mutations was 97.7% and specificity was 90.8%, which increased to 99.0% after DNA sequencing analysis of the discordant samples. Of the 1,096 subjects in the four clinical studies, 49% were from the US. Overall, Xpert detected MTBc in 439 of 468 culture-positive specimens for a sensitivity of 93.8% (95% confidence interval [CI]: 91.2%-95.7%) and did not detect MTBc in 620 of 628 culture-negative specimens for a specificity of 98.7% (95% CI: 97.5%-99.4%). Sensitivity was 99.7% among smear-positive cases, and 76.1% among smear-negative cases. Non-determinate MTBc detection and false-positive RIF resistance results were low (1.2 and 0.9%, respectively). CONCLUSIONS: The updated Xpert assay retained the high sensitivity and specificity of the previous assay versions and demonstrated low rates of non-determinate and RIF resistance false positive results.Source
BMC Infect Dis. 2016 Dec 20;16(1):764. Link to article on publisher's siteDOI
10.1186/s12879-016-2039-4Permanent Link to this Item
http://hdl.handle.net/20.500.14038/40223PubMed ID
27993132Related Resources
Link to Article in PubMedRights
© The Author(s). 2016.Distribution License
http://creativecommons.org/licenses/by/4.0/ae974a485f413a2113503eed53cd6c53
10.1186/s12879-016-2039-4