Characterization of the embB gene in Mycobacterium tuberculosis isolates from Barcelona and rapid detection of main mutations related to ethambutol resistance using a low-density DNA array

Authors:
Open Access
Publisher website
Google Scholar
Abstract
Ethambutol resistance has mostly been related to mutations in the embB gene. The objective of the present study was to characterize the embB gene in a collection of ethambutol-resistant and ethambutol-susceptible isolates of Mycobacterium tuberculosis complex (MTBC) from Barcelona, and to develop a DNA microarray for the rapid detection of embB mutations in our area. Fifty-three ethambutol-resistant and 702 ethambutol-susceptible isolates of MTBC were sequenced in internal 982–1495 bp fragments of the embB gene. In addition, a low-cost, low-density array was designed to include the embB codons identified as being most frequently mutated in our area (LD-EMB array). The global prevalence of embB mutations found among the ethambutol-resistant isolates was 77.4% (41/53). Substitutions in embB306 were the most common [53.7% (22/41)], followed by substitutions in embB406 [26.8% (11/41)]. The presence of mutations in embB406 was related to higher levels of ethambutol resistance and to multidrug resistance. Among unrelated isolates (from 24-locus MIRU-VNTR genotyping), the percentage of embB-mutated isolates was 72.9% (27/37)—59.3% (16/27) in embB306 and 25.9% (7/27) in embB406. None of the ethambutol-susceptible isolates studied showed a mutation in codon 306 or 406. The LD-EMB array showed 100% sensitivity and specificity in identifying the main embB substitutions in our area. Mutations at codons 306 and 406 of embB have a relevant role in resistance to ethambutol in our area. The LD-EMB array developed in this study would appear to be a good molecular test for rapid detection of ethambutol resistance.

This publication has 25 references indexed in Scilit: