Treatment Responses of Early Syphilis to Ceftriaxone Plus Doxycycline

Overview

In a prospective study investigating the prevalence of sexually transmitted infections (STIs) among at-risk people living with HIV (PLWH), the prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae was 24.7% and 12.1%, respectively. Surprisingly, the study found high rates of C. trachomatis and/or N. gonorrhoeae co-infections in PLWH with recent hepatitis C virus (HCV) infection (50%), HBsAg positivity (44%), and early syphilis (36%). Considering the high rate of sexually transmitted co-infections, combination therapy of single-dose ceftriaxone plus 7-day doxycycline for early syphilis may provide convenience and benefit to treatment of N. gonorrhoeae and C. trachomatis co-infections at a single clinic encounter. In the present study, this study aim to compare the efficacy of ceftriaxone plus doxycycline versus benzathine penicillin G (BPG) plus doxycycline as the treatment for early syphilis among PLWH.

Enrolled criteria: 1. PLWH aged 20 years or more 2. PLWH with early syphilis (i.e. primary, secondary, or early latent syphilis), confirmed by a positive rapid plasma reagin (RPR) titer with a reactive Treponema pallidum particle agglutination (TPPA) assay. 3. PLWH has provided informed consent \*A participant with repeated syphilis can be repeated enrolled after signing an informed consent if the previous episode of early syphilis was successfully treated with achieving at least a 4-fold decrease in RPR titers and 48-week follow-up is completed. Exclusion criteria: 1. PLWH with RPR titers of less than 4 2. Exposure to antibiotics with activity against T. pallidum, such as penicillins, third-generation cephems, doxycycline, or macrolides, within the preceding 4 weeks 3. A known or suspected infection other than syphilis requiring additional treatment with an antimicrobial active against T. pallidum 4. A history of intolerance to penicillin, ceftriaxone, or doxycycline 5. Pregnancy Primary outcome: Serologic response at month 6 (defined as either a 4-fold or greater decline in RPR titer compared to baseline or being RPR-nonreactive) Secondary outcomes: 1. Microbiologic response of syphilis (defined as T. pallidum PCR Ct value \>38) at week 4 2. Microbiologic response of bacterial STIs (defined as negative PCR results) at week 4 3. Serologic response at months 3 and 12 4. Safety of study treatment recorded by using a diary (all adverse events will be coded and graded according to Common Terminology Criteria for Adverse Events \[CTCAE\] v4.0.) 5. Adherence evaluation (the noting of tablet intake in the diary for the 7 days of the treatment period)