Isolation of Mycobacterium tuberculosis Strains with a Silent Mutation in rpoB Leading to Potential Misassignment of Resistance Category

Abstract
Our study provides an alert regarding the transmission of rifampin-susceptible strains of Mycobacterium tuberculosis with a silent substitution in codon 514 of rpoB . Among 1,450 cases, we identified 12 isolates sharing this mutation and related restriction fragment length polymorphism (RFLP) types. The mutation impaired hybridization with the wild-type probes in three independent commercial assays, which could lead to misassignment of resistance.