Decreased Susceptibility to Azithromycin and Doxycycline in Clinical Isolates of Chlamydia trachomatis Obtained from Recurrently Infected Female Patients in India

Abstract

Background: Recurrent genital Chlamydia trachomatis infection often results in serious sequelae and has a major impact on reproductive health. Materials and Methods: Recurrent infections were determined in symptomatic female patients. In vitro susceptibility assay was performed for azithromycin and doxycycline using the cell culture technique against 21 clinical isolates obtained from C. trachomatis-positive patients including those who were recurrently infected. Results: Thirteen isolates (61.9%) were found to be susceptible to azithromycin and doxycycline with minimum inhibitory concentration (MIC) values ≤0.125 and ≤0.25 µg/ml, respectively. Eight isolates (38%) were found to be less susceptible to the drugs. Two of them had MICs of 8 µg/ml for both the drugs and could not be completely eradicated as observed by minimum bactericidal concentration assay. Conclusions: Decreased antibiotic susceptibility to the current first-line drugs (azithromycin and doxycycline) for chlamydial infection treatment was observed in isolates obtained from recurrently infected patients.