Elmira Gurbanova1,2, Rafail Mehdiyev1, Kai Blondal3, Rasim Tahirli1, Fuad Mirzayev4, Doris Hillemann5, Asker Ismayilov1, Alan Altraja2,6. 1. 1 Main Medical Department, Azerbaijan Ministry of Justice, Baku, Azerbaijan . 2. 2 Department of Pulmonary Medicine, University of Tartu , Tartu, Estonia . 3. 3 Department of Communicable Disease Prevention and Control, Reykjavik Health Care Services , Reykjavik, Iceland . 4. 4 World Health Organization, Geneva, Switzerland . 5. 5 Supra-National Reference Laboratory , Borstel, Germany . 6. 6 Lung Clinic, Tartu University Hospital , Tartu, Estonia .
Abstract
BACKGROUND: Simultaneous use of genotypic and phenotypic diagnostic tools for detection of rifampicin (RIF) susceptibility may yield discrepant results. OBJECTIVE: To measure the discordance between the RIF-susceptibility results by Xpert MTB/RIF and Mycobacterium Growth Indicator Tube (MGIT), to evaluate if application of both tests to the same sample affects the discrepancy, and to evaluate treatment outcome in patients with the discordant strains. DESIGN: Sputa from patients with tuberculosis managed in the penitentiary system of Azerbaijan during 2011-2015 were examined for RIF susceptibility using Xpert MTB/RIF and MGIT. Strains with discrepant results were sequenced. RESULTS: Of 532 patients included, 6.2% had discordant RIF-susceptibility results. No significant association of the discordant RIF-susceptibility results with application of both tests on one sample versus sequential samples was found. L511P mutation accounted significantly (p = 0.006) for the discrepancy among those RIF resistant on Xpert MTB/RIF, but sensitive on MGIT. No significant association was identified between the outcomes of treatment with the first- or second-line drugs and the presence of any mutation. CONCLUSION: The Xpert MTB/RIF and MGIT testing may be used in sequential sputum samples without increase in the RIF-susceptibility discordance rate. L511P mutation significantly accounts for discordant RIF-susceptibility results, but its clinical relevance may be low.
BACKGROUND: Simultaneous use of genotypic and phenotypic diagnostic tools for detection of rifampicin (RIF) susceptibility may yield discrepant results. OBJECTIVE: To measure the discordance between the RIF-susceptibility results by Xpert MTB/RIF and Mycobacterium Growth Indicator Tube (MGIT), to evaluate if application of both tests to the same sample affects the discrepancy, and to evaluate treatment outcome in patients with the discordant strains. DESIGN: Sputa from patients with tuberculosis managed in the penitentiary system of Azerbaijan during 2011-2015 were examined for RIF susceptibility using Xpert MTB/RIF and MGIT. Strains with discrepant results were sequenced. RESULTS: Of 532 patients included, 6.2% had discordant RIF-susceptibility results. No significant association of the discordant RIF-susceptibility results with application of both tests on one sample versus sequential samples was found. L511P mutation accounted significantly (p = 0.006) for the discrepancy among those RIF resistant on Xpert MTB/RIF, but sensitive on MGIT. No significant association was identified between the outcomes of treatment with the first- or second-line drugs and the presence of any mutation. CONCLUSION: The Xpert MTB/RIF and MGIT testing may be used in sequential sputum samples without increase in the RIF-susceptibility discordance rate. L511P mutation significantly accounts for discordant RIF-susceptibility results, but its clinical relevance may be low.
Entities:
Keywords:
Mycobacterium tuberculosis; drug resistance; mutation; rifampin; sputum; treatment outcome
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