Institute of Tropical Medicine Antwerp
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Mycobacterium tuberculosis strains with highly discordant rifampin susceptibility test results

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Show simple item record Van Deun, A. Barrera, L. Bastian, I. Fattorini, L. Hoffmann, H. Kam, K. M. Rigouts, L. Rüsch-Gerdes, S. Wright, A. 2009-12-22T10:41:14Z 2009-12-22T10:41:14Z 2009
dc.identifier.issn 0095-1137
dc.identifier.other ITG-M1B
dc.identifier.other ITG-M7A
dc.identifier.other MICRO
dc.identifier.other U-MYCOB
dc.identifier.other JIF
dc.identifier.other DOI
dc.identifier.other UPD17
dc.identifier.other ABSTRACT
dc.description.abstract The objectives of this study were to investigate the origin of highly discordant rifampin (rifampicin) (RMP) drug susceptibility test results obtained for Mycobacterium tuberculosis strains during proficiency testing. Nine Supra-National Tuberculosis Reference Laboratories tested the RMP susceptibilities of 19 selected M. tuberculosis strains, using standard culture-based methods. The strains were classified as definitely resistant (R) (n = 6) or susceptible (S) (n = 2) or probably resistant (PR) (n = 8) or susceptible (PS) (n = 3) based on rpoB mutations and treatment outcome. All methods yielded a susceptible result for the two S and three PS strains lacking an rpoB mutation and a resistant result for one R strain with a Ser531Leu mutation and one PR strain with a double mutation. Although the remaining 12 R and PR strains had rpoB mutations (four Asp516Tyr, three Leu511Pro, two Leu533Pro, one each His526Leu/Ser, and one Ile572Phe), they were all susceptible by the radiometric Bactec 460TB or Bactec 960 MGIT methods. In contrast, only one was susceptible by the proportion method on Löwenstein-Jensen medium and two on Middlebrook 7H10 agar. Low-level but probably clinically relevant RMP resistance linked to specific rpoB mutations is easily missed by standard growth-based methods, particularly the automated broth-based systems. Further studies are required to confirm these findings, to determine the frequency of these low-level-resistant isolates, and to identify technical improvements that may identify such strains. en
dc.language English en
dc.subject Bacterial diseases en
dc.subject Tuberculosis en
dc.subject Mycobacterium tuberculosis en
dc.subject Strains en
dc.subject Mutations en
dc.subject Rifampicin en
dc.subject Drug sensitivity testing en
dc.title Mycobacterium tuberculosis strains with highly discordant rifampin susceptibility test results en
dc.type Article en
dc.citation.issue 11 en
dc.citation.jtitle Journal of Clinical Microbiology en
dc.citation.volume 47 en
dc.citation.pages 3501-3506 en
dc.citation.jabbreviation J Clin Microbiol en

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