Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> 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 <i>Mycobacterium tuberculosis</i&...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-07-01
|
| Series: | Pathogens |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-0817/12/7/909 |
| _version_ | 1797587889494687744 |
|---|---|
| author | Carine Bokop Lindiwe M. Faye Teke Apalata |
| author_facet | Carine Bokop Lindiwe M. Faye Teke Apalata |
| author_sort | Carine Bokop |
| collection | DOAJ |
| description | 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 <i>Mycobacterium tuberculosis</i> by Xpert<sup>®</sup> 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 (<i>p</i> < 0.001). In conclusion, laboratory errors should be considered when investigating discordant results. |
| first_indexed | 2024-03-11T00:45:13Z |
| format | Article |
| id | doaj.art-b7ea2bb646a04390bed6ff7606b03610 |
| institution | Directory Open Access Journal |
| issn | 2076-0817 |
| language | English |
| last_indexed | 2024-03-11T00:45:13Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Pathogens |
| spelling | doaj.art-b7ea2bb646a04390bed6ff7606b036102023-11-18T20:50:45ZengMDPI AGPathogens2076-08172023-07-0112790910.3390/pathogens12070909Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in MthathaCarine Bokop0Lindiwe M. Faye1Teke Apalata2Division of Medical Microbiology, Department of Laboratory Medicine and Pathology, Faculty of Health Sciences, Walter Sisulu University, Mthatha 5099, Eastern Cape, South AfricaDepartment of Laboratory Medicine and Pathology, Faculty of Health Sciences and National Health Laboratory Services (NHLS), Walter Sisulu University, Mthatha 5099, Eastern Cape, South AfricaDepartment of Laboratory Medicine and Pathology, Faculty of Health Sciences and National Health Laboratory Services (NHLS), Walter Sisulu University, Mthatha 5099, Eastern Cape, South AfricaThe 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 <i>Mycobacterium tuberculosis</i> by Xpert<sup>®</sup> 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 (<i>p</i> < 0.001). In conclusion, laboratory errors should be considered when investigating discordant results.https://www.mdpi.com/2076-0817/12/7/909Xpert MTB/RIFline probe assayMGIT 960 system<i>Mycobacterium tuberculosis</i>discrepant results |
| spellingShingle | Carine Bokop Lindiwe M. Faye Teke Apalata Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in Mthatha Pathogens Xpert MTB/RIF line probe assay MGIT 960 system <i>Mycobacterium tuberculosis</i> discrepant results |
| title | Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in Mthatha |
| title_full | Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in Mthatha |
| title_fullStr | Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in Mthatha |
| title_full_unstemmed | Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in Mthatha |
| title_short | Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant <i>Mycobacterium tuberculosis</i> Isolated from Healthcare Facilities in Mthatha |
| title_sort | analysis of discordance between genotypic and phenotypic assays for rifampicin resistant i mycobacterium tuberculosis i isolated from healthcare facilities in mthatha |
| topic | Xpert MTB/RIF line probe assay MGIT 960 system <i>Mycobacterium tuberculosis</i> discrepant results |
| url | https://www.mdpi.com/2076-0817/12/7/909 |
| work_keys_str_mv | AT carinebokop analysisofdiscordancebetweengenotypicandphenotypicassaysforrifampicinresistantimycobacteriumtuberculosisiisolatedfromhealthcarefacilitiesinmthatha AT lindiwemfaye analysisofdiscordancebetweengenotypicandphenotypicassaysforrifampicinresistantimycobacteriumtuberculosisiisolatedfromhealthcarefacilitiesinmthatha AT tekeapalata analysisofdiscordancebetweengenotypicandphenotypicassaysforrifampicinresistantimycobacteriumtuberculosisiisolatedfromhealthcarefacilitiesinmthatha |