Correlation of the phenotypic ethambutol susceptibility of Mycobacterium tuberculosis with embB gene mutations in Korea

Young Kil Park, Sung Weon Ryoo, Seung Heon Lee, Hum Nath Jnawali, Chang Ki Kim, Hee Jin Kim, Sang Jae Kim

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The phenotypic resistance to ethambutol (EMB) in Mycobacterium tuberculosis with embB gene mutations is still unclear. This study was designed to better understand EMB resistance due to embB gene mutation. Sequencing analysis of the embB gene was performed for 124 EMBsusceptible and 93 EMB-resistant M. tuberculosis strains isolated from South Korea. The MIC was determined for EMB-susceptible M. tuberculosis strains with the embB mutation and wildtype on Lö wenstein-Jenson (LJ) solid medium in duplicate. Two (2.8%) of 72 pan-susceptible, two (9.1%) of 22 any-drug-resistant but EMB-susceptible, nine (30.0%) of 30 multidrugresistant (MDR) but EMB-susceptible and 84 (90.3%) of 93 EMB-resistant M. tuberculosis strains possessed embB mutations at various codons including 306, 319, 354, 360, 399, 405, 406, 459 and 497. Strains with embB mutations at codons 306, 354, 399, 405 and 497 had highly pronounced EMB resistance, while strains with mutations at codons 319 and 406 mutations were moderately resistant and those with an embB459 mutation were EMBsusceptible at the critical concentration (2.0 μg ml 1) on LJ solid medium. However, the mean MIC for strains with embB mutations (1.42 μg ml 1) was higher than that for strains without the embB mutation (1.0 μg ml 1) in EMB-susceptible M. tuberculosis isolates (P50.0052). Three novel embB mutations at codons 399, 405 and 459 were identified in this study. These results support the hypothesis that embB mutation except for a few specific mutation types may be the main cause of EMB resistance.

Original languageEnglish
Pages (from-to)529-534
Number of pages6
JournalJournal of Medical Microbiology
Volume61
Issue number4
DOIs
Publication statusPublished - 2012 Apr 1
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

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