<italic>rpoB</italic> gene mutations among <italic>Mycobacterium tuberculosis</italic> isolates from extrapulmonary sites.

The aim of this study was to analyze mutations occurring in the <italic>rpoB</italic> gene of <italic>Mycobacterium tuberculosis</italic> (MTB) isolates from clinical samples of extrapulmonary tuberculosis (EPTB). Seventy formalin‐fixed, paraffin‐embedded samples and fresh tissue samples from confirmed EPTB cases were analyzed. Nested PCR based on the <italic>rpoB</italic> gene was performed on the extracted DNAs, combined with cloning and subsequent sequencing. Sixty‐seven (95.7%) samples were positive for nester PCR. Sequence analysis of the 81 bp region of the <italic>rpoB</italic> gene demonstrated mutations in 41 (61.2%) of 67 sequenced samples. Several point mutations including deletion mutations at codons 510, 512, 513 and 515, with 45% and 51% of the mutations in codons 512 and 513 respectively were seen, along with 26% replacement mutations at codons 509, 513, 514, 518, 520, 524 and 531. The most common alteration was Gln → His, at codon 513, presented in 30 (75.6%) isolates. This study demonstrated sequence alterations in codon 513 of the 81 bp region of the <italic>rpoB</italic> gene as the most common mutation occurred in 75.6% of molecularly confirmed rifampin‐resistant strains. In addition, simultaneous mutation at codons 512 and 513 was demonstrated in 34.3% of the isolates. [ABSTRACT FROM AUTHOR]