Time to Clearance of Ribosomal RNA Using Transcription-mediated Amplification in Women Treated for Chlamydial Infection

Background:
Recommendations from the Centers for Disease Control and Prevention (CDC) suggest that women treated for Chlamydia trachomatis (CT) wait at least 3 weeks before being tested for cure. This recommendation is based on expert opinion, as the duration of CT detection following treatment is uncertain. Prior studies have demonstrated that DNA-based tests may remain positive for up to 2 weeks following treatment. Transcription-mediated amplification (TMA) amplifies CT ribosomal RNA (rRNA) and has improved sensitivity compared to the DNA-based assays. The time to clearance of rRNA following treatment for chlamydial infection is unknown.

Objective:
To evaluate the time to clearance of rRNA following treatment for cervical chlamydial infection using TMA on self-collected vaginal swabs, in order to evaluate TMA as a possible test-of-cure.

Method:
Twenty women with cervical chlamydia diagnosed with a positive TMA urine test self-obtained a vaginal swab on the day of treatment (day 0) and on days 3, 7, 10 and 14 following treatment with 1 gram of azithromycin. Sixteen subjects reported abstinence during the fourteen-day period and were included in the analysis.

Result:
Twelve of 16 subjects (75%) had a negative swab at day 14. The median time to a negative vaginal TMA in these subjects was 10 days. Subjects with a negative TMA at each timepoint were as follows: 0/16 (0%) on day 0, 2/16 (12.5%) on day 3, 6/16 (37.5%) on day 7, 12/16 (75%) on day 10, and 12/16 (75%) on day 14.

Conclusion:
After treatment, chlamydia rRNA by TMA declined with time. As rRNA was undetectable in only 75% of the subjects fourteen days after treatment, TMA should not be used as a test-of-cure in the fourteen-day period following treatment.

Implications:
Given the sensitivity of TMA for persistent chlamydia rRNA, at least 2 weeks must elapse before repeat testing for test-of-cure is warranted.