Background: There are ongoing concerns about treatment failure with azithromycin for the treatment of rectal chlamydia. Aim: To investigate treatment efficacy of two treatments for rectal chlamydial infection. Methods: We performed a retrospective analysis of all patients diagnosed with rectal chlamydial infection between 2009 and 2015 in Adelaide, Australia. Patients were treated with either azithromycin (1 g single dose) or doxycycline (100 mg twice a day for 10 days) and returned for repeat testing 14–180 days after treatment commenced. Log-binomial models were used to estimate the relative risk (RR) of recurrent rectal chlamydia associated with the treatment with azithromycin versus doxycycline. Results: In men, rectal chlamydia prevalence was 6.7%, and in women, it was 8.1%. Of the 526 patients diagnosed with rectal chlamydial infections, 419 (79.7%), 93 (17.7%) and 14 (2.6%) patients were treated with doxycycline, azithromycin or other medication respectively. Of these patients, 173 (41.3%) of 419 doxycycline-treated patients and 31 (33.3%) of 93 azithromycin-treated patients were retested between 14 and 180 days after treatment commenced (P = 0.16). Among these patients, the repeat rectal chlamydia test was less commonly positive in those treated with doxycycline (5.8%; 95% confidence interval (CI) 0.03–0.10) compared with those treated with azithromycin (19.4%; 95% CI 0.09–0.36) and (P = 0.01). In the multivariate analysis, azithromycin-treated patients had a significantly higher risk of a positive test in the 14 and 180 days after treatment commenced (adjusted relative risk (aRR) 2.96, 95% CI 1.16–7.57). Conclusion: The findings suggest that doxycycline may be more effective than azithromycin in treating rectal chlamydial infections.
- Chlamydia trachomatis