Analysis of discrepant results between the Genotype® MTBDRplus assay and an antimicrobial drug susceptibility test for isoniazid-resistant tuberculosis. (January 2017)

• Record Type: Journal Article
• Authors: Jo, Kyung-Wook; Yeo, Yoomi; Sung, Heungsup; Kim, Mi-Na; Shim, Tae Sun
• Is Part Of: Respiratory medicine. Volume 122(2017)
• Page Start: 12
• Page End: 17
• Publication Date: 2017-01
• Subjects: Isoniazid -- Discrepancy -- MTBDRplus assay -- KatG gene sequencing -- inhA gene sequencing; Chest -- Diseases -- Periodicals; Chest -- Diseases -- Great Britain -- Periodicals; Respiratory organs -- Diseases -- Periodicals; Respiratory Tract Diseases -- Periodicals; Appareil respiratoire -- Maladies -- Périodiques; Thorax -- Maladies -- Périodiques; Appareil respiratoire -- Maladies -- Traitement -- Périodiques; Electronic journals; 616.2
• DOI: 10.1016/j.rmed.2016.11.016
• Languages: English
• ISSNs: 0954-6111

Abstract

Abstract: Background: We investigated discrepant results determined using the Genotype ® MTBDR plus assay and a conventional antimicrobial drug susceptibility test (ADST) for isoniazid (INH) resistance using sequencing analysis and analyzed the clinical course of patients with discrepant results. Methods: Among 1373 MTBDR plus assays performed at our tertiary referral center in South Korea between August 2009 and December 2015, the results for 46 (3.4%) differed from those for ADST. KatG and inhA gene sequencing analysis results were available for 23 patients. ADSTs were carried out using the absolute concentration method with Löwenstein–Jensen media. Results: Results from 11 patients indicated INH susceptibility by MTBDR plus assay and INH resistance by ADST. For 5 of these patients, sequencing revealed no evidence of mutations, whereas specific mutations were detected in the remaining 6 patients. These should have been detected using the MTBDR plus assay. The other 12 patients had isolates with the opposite discrepancy, that is INH resistance by MTBDR plus assay but INH susceptibility by ADST. For 7 of these cases, sequencing results were consistent with those of the MTBDR plus assay. However, sequencing analysis did not explain the discrepancies in the remaining 5 patients. All 23 patients with discrepant results received individualized treatment regimens determined by the attending physician according to their test results and susceptibility to other drugs, such as rifampin. Good outcomes were reported for the majority. Conclusion: Discrepancies between test results for INH resistance on the MTBDR plus assay and ADST appear to be infrequent. Gene sequencing analysis is useful for identifying the cause of the discrepancy.