Pyrosequencing for rapid detection of tuberculosis resistance to Rifampicin and Isoniazid in Syrian and Lebanese clinical isolates.

Background: Rapid and accurate techniques are always welcomed for the detection of resistant strains of Mycobacterium tuberculosis MTB.
Objectives: The objective of this study is to evaluate the pyrosequencing technology for the detection of MTB resistance to Rifampicin (RIF) and Isoniazid (INH) in Syrian and Lebanese clinical strains; 66 strains resistant to INH, among them 56 resistant also to RIF, were tested.
Methods: Four pyrosequencing assays were optimized and applied to the following loci: rpoBrpoB RIF resistance-determining region, katG, the promoter regions of inhA and ahpC-oxyR intergenic region.
Results: The prevalence of mutations on codon 315 of the katG gene, inhA and ahpc-oxyR were 42.4%, 21.2% and 9.0%, respectively, which make an overall sensitivity of 72.6% for INH resistance. All RIF-resistant strains contained at least one non-synonymous codon change in the sequenced rpoB region (507-533) relative to the ATCC reference strain. The RIF drug resistance region (RRDR) sequencing identified 96 modified codons representing 34 different mutations.
Conclusions: The high sensitivity and the short turnaround time combined with multilocus sequencing of several isolates in parallel make pyrosequencing an attractive method for drug resistance screening for MTB.
(Copyright © 2015 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.)