Background: Treatment failure rates after the recommended 1 g azithromycin among Chlamydia trachomatis (Ct)-infected men have ranged from (5%-23%) in 3 recent studies. Reasons for the disparate results are unclear. Methodological issues or geographic differences may account for this inconsistency. The purpose of this study was to conduct a secondary analysis of combined data from three studies, removing the confounding effects of premature test-of-cure (TOC) and sexual re-exposure comparing the rates by geographic location.
Methods: Data from cohorts of men in 4 U.S. cities who received 1 g azithromycin under directly observed therapy (DOT) for the treatment of uncomplicated Ct infections were pooled. Baseline/TOC was performed using Gen-Probe APTIMA Combo 2 (GPAC-2) NAAT urine test. Sexual re-exposure was elicited via ACASI survey for all but Birmingham which was provider-elicited. Men who were GPAC-2+ prior to 3 weeks were excluded from analysis. Rates of re-test positive were compared for men who denied sex or used a condom for all sex acts to those who reported sexual re-exposure/new exposure.
Results: Among 323 included, pooled crude and weighted Ct re-test positive rates were 9.0% and 14.9%. Rates varied by city: New Orleans 13/225 (5.8%), Jackson 2/33 (6.1%), Seattle 8/45 (17.8%), and Birmingham 6/27 (22.2%). Rates of sexual re-exposure were: New Orleans (51.1%), Jackson (45.5%), Seattle (33.3%) and Birmingham (8.3%). In pooled analyses, re-test positive rates among those who reported no sexual exposure were 8.5% (95% C.I. 5.4%-12.8%) and among those who reported sexual exposure 9.5% (95% C.I. 5.5%-12.7%).
Conclusions: Overall treatment failure was 9.0% and varied by geographic location (range 5.8%-22.2%) and re-infection did not appear to account for this. Given that test-of-cure is not recommended for Ct infections, this rate is of concern. Susceptibility testing should be performed to determine if sensitivity to azithromycin has declined and/or varies by region.