Sexually transmitted infections (STIs) are a global concern, with C. trachomatis a major pathogen responsible for urethritis, epididymitis, cervicitis, and pelvic inflammatory disease. While resistance has not been high, a few cases of unsuccessful treatment have been reported worldwide, emphasising the need for continual antimicrobial monitoring. Therefore an intensive nationwide surveillance of C. trachomatis susceptibility was carried out in Japan, with isolates taken from 51 and 38 hospitals and clinics in 2009 and 2012, respectively.
The study included males with non-gonococcal urethritis, or chlamydial urethritis; 207 urethral discharge specimens were collected in 2009 and 223 in 2012. C. trachomatis was isolated from 48 specimens in 2009 and 2012, with the MIC determined for 19 and 39 isolates, respectively.
Sitafloxacin had the lowest MIC value of all the fluoroquinolones tested, with activity maintained in both 2009 and 2013 (0.063 μg/ml and 0.063 μg/ml). In comparison the MICs for tosufloxacin, levofloxacin and ciprofloxacin were 0.125μg/ml and 0.125μg/ml; 0.5 μg/ml and 0.5 μg/m; 2 μg/ml and 1 μg/ml, respectively.
The MICs for minocycline and doxycycline were almost the same at 0.063 μg/ml and 0.063 μg/ml, and 0.125 μg/ml and 0.125 μg/ml, respectively. Among the macrolides, clarithromycin had the lowest MIC, (0.016 μg/ml and 0.016 μg/ml).
Researchers concluded that no resistant strains of C. trachomatis were identified against fluoroquinolones, tetracycline, or macrolide agents in Japan. However, due to global reports of decreased efficacy for azithromycin, surveillance should be maintained.
J Infect Chemother. 2016 Sep;22(9):581-6. doi: 10.1016/j.jiac.2016.06.010.