Doxycycline provides better cure for Anogenital Chlamydia in Women compared to Azithromycin

A new study published in The Lancet Infectious Diseases suggests that women who got a single dosage of azithromycin had a substantially lower microbiological anorectal cure rate than those who received a 1-week course of doxycycline.

Chlamydia trachomatis anorectal infections are frequent in women. Although doxycycline and azithromycin have equal efficacy in the treatment of urogenital infection, their efficacy in the treatment of anorectal infection is unknown. Olivia Peuchant and colleagues designed this trial to evaluate a single dose of azithromycin to a 7-day course of doxycycline for the management of anorectal C trachomatis infection in women with concomitant vaginal infection.

In France, a multicenter, open-label, randomized, controlled superiority study comprising four sexually transmitted infection screening centers and three pregnancy termination centers was conducted. Sexually active adult women (18 years) who volunteered to submit self-collected anorectal swabs for C trachomatis identification were included for this study. Participants were randomly allocated (1:1) to receive azithromycin (a single 1-g dosage, with or without meals) or doxycycline orally, utilizing block sizes of six and eight with stratification by each investigating site. All laboratory personnel who performed bacteriological studies, but not participants or investigators, were blinded to the treatment groups. The primary outcome was the microbiological anorectal cure rate, which was determined as a C trachomatis-negative nucleic acid amplification test (NAAT) result in anorectal specimens 6 weeks after therapy beginning in women who had a C trachomatis-positive anorectal NAAT result at baseline. The primary analysis was performed in a modified intention-to-treat population using multiple imputation, which comprised all women who were randomly assigned and had C trachomatis-positive vaginal and anorectal NAAT results at baseline. Adverse events were reported by all women who were randomly assigned.

The key findings of this study were as follow:

1. Between October 19, 2018, and April 17, 2020, we assigned randomly 460 individuals to either the doxycycline (n=230) or azithromycin (n=230) groups.

2. Four (1%) of the 460 individuals were eliminated because they refused to take doxycycline or were deemed ineligible following randomization.

3. At baseline, 357 (78%) of the 456 patients had a concurrent C trachomatis-positive anorectal NAAT result; 184 (52%) of the 357 were in the doxycycline group, and 173 (48%) were in the azithromycin group.

4. Microbiological anorectal cure occurred in 147 (94%) of 156 doxycycline group individuals (28 missing values) vs 120 (85%) of 142 azithromycin group participants.

5. Adverse events likely related to therapy were reported by 53 (12%) of 456 women: 24 (11%) of 228 in the doxycycline group and 29 (13%) of 228 in the azithromycin group.

6. Gastrointestinal issues were the most common, affecting 43 (9%) of 456 women: 17 (8%) of 228 in the doxycycline group and 26 (11%) of 228 in the azithromycin group.

In conclusion, this data shows that doxycycline should be used as first-line treatment in women with C trachomatis infection.

Reference: Peuchant, O., Lhomme, E., Martinet, P., Grob, A., Baïta, D., Bernier, C., Gibaud, S. A., Le Hen, I., Le Naour, E., Trignol-Viguier, N., Lanotte, P., Galet, J. (2022). Doxycycline versus azithromycin for the treatment of anorectal Chlamydia trachomatis infection in women concurrent with vaginal infection (CHLAZIDOXY study): a multicentre, open-label, randomised, controlled, superiority trial. In The Lancet Infectious Diseases. Elsevier BV. https://doi.org/10.1016/s1473-3099(22)00148-7