In vitro activity of rifampin against and rpoB mutations in Chlamydia trachomatis clinical isolates

Abstract

Objective To evaluate the susceptibility of Chlamydia trachomatis clinical isolates to rifampin, and assess the relationship between rpoB mutations and antibiotic resistance in them. Methods A microculture method was used to determine the minimal inhibitory concentration (MIC) of rifampin in 52 Chlamydia trachomatis clinical isolates. The rpoB gene was amplified from all the clinical isolates and a standard strain of Chlamydia trachomatis followed by single-strand conformation polymorphism (SSCP) analysis. Sequencing of PCR products was carried out for two clinical isolates. Results No rifampin-resistant strain was found among these clinical isolates. The MIC of rifampin varied from 0.004 to 0.030 mg/L. Neither SSCP analysis nor sequencing showed rpoB mutations. Conclusions No rpoB mutations were found in Chlamydia trachomatis isolates from patients unresponsive to rifampin. The unresponsiveness to rifampin may be attributed to multiple factors. Key words: Chlamydia trachomatis; Rifampin; Microbial sensitivity tests; Drug resistance, microbial; DNA mutational analysis; Genes, rpoB