Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant Mycobacterium tuberculosis Isolated from Healthcare Facilities in Mthatha

The study sought to determine the rate of discordant results between genotypic and phenotypic tests for the diagnosis of drug-resistant tuberculosis (DR-TB). Sputum samples and cultured isolates from suspected DR-TB patients were, respectively, analyzed for by Xpert MTB/RIF (Cepheid, Sunnyvale, CA,...

Full description

Saved in:
Bibliographic Details
Published in:Pathogens (Basel) 2023-07, Vol.12 (7), p.909
Main Authors: Bokop, Carine, Faye, Lindiwe M, Apalata, Teke
Format: Article
Language:English
Subjects:
Contamination
Discordance
discrepant results
DNA
Drug resistance
Errors
Genes
Germany
Health care facilities
health services
HIV
Human immunodeficiency virus
Infections
Isoniazid
Laboratories
line probe assay
MGIT 960 system
Mutation
Mycobacterium tuberculosis
New York
phenotype
rifampicin
Rifampin
Sputum
Tuberculosis
Xpert MTB/RIF
Citations: Items that this one cites
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The study sought to determine the rate of discordant results between genotypic and phenotypic tests for the diagnosis of drug-resistant tuberculosis (DR-TB). Sputum samples and cultured isolates from suspected DR-TB patients were, respectively, analyzed for by Xpert MTB/RIF (Cepheid, Sunnyvale, CA, USA) and line probe assays (LPA) (Hain, Nehren, Germany). Discrepant rifampicin (RMP)-resistant results were confirmed using BACTEC MGIT960 (BD, New York, NY, USA). Of the 224 RMP-resistant results obtained by Xpert MTB/RIF, 5.4% were susceptible to RMP by LPA. MGIT960 showed a 75% agreement with LPA. The discrepancy was attributed to either heteroresistance or DNA contamination during LPA testing in 58.3% of cases. In 25% of the samples showing agreement in RMP resistance between Xpert MTB/RIF and MGIT960, the discrepancy was attributed to laboratory errors causing false RMP susceptible results with LPA. In 16.7% of the cases, the discrepancy was attributed to false RMP susceptible results with Xpert MTB/RIF. Out of the 224 isolates, susceptibility to isoniazid (INH) by LPA was performed in 73.7% RMP-resistant isolates, of which, 80.6% were resistant. All RMP-resistant isolates by Xpert MTB/RIF were confirmed in 98.5% by LPA if TB isolates were resistant to INH, but were only confirmed in 81.3% if TB isolates were susceptible to INH ( < 0.001). In conclusion, laboratory errors should be considered when investigating discordant results.
ISSN:2076-0817
2076-0817
DOI:10.3390/pathogens12070909