Efficacy and Safety of Treatments for Different Stages of Syphilis: a Systematic Review and Network Meta-Analysis of Randomized Controlled Trials and Observational Studies

Parenteral penicillin is the first-line regimen for treating syphilis. However, allergic reactions and poor drug tolerance still present challenging problems with respect to use of this antibiotic. This study aimed to evaluate the efficacy and safety of ceftriaxone, erythromycin, minocycline, tetracycline, and doxycycline for syphilis treatment, compared with penicillin, to determine which antibiotic could be a better substitute for penicillin. This study included 17 articles, comprising 3 randomized controlled trials (RCTs) and 14 observational studies and involving 4,485 syphilis patients. Estimated risk ratios (RRs) and 95% confidence interval (CIs) were used to compare the serological response rates. At the 6- and 12-month follow-ups, the serological response rates were compared by direct meta-analysis and network meta-analysis (NMA). Based on direct meta-analysis, the serological response rates at the 3- and 24-month follow-ups were compared. Our NMA showed a higher serological response rate for ceftriaxone than for penicillin at the 6-month follow-up (RR of 1.12, 95% CI of 1.02 to 1.23). Ceftriaxone was equally effective as penicillin for syphilis in terms of serological response rates, and it was a better substitute for penicillin than ceftriaxone, erythromycin, minocycline, tetracycline, or doxycycline. However, more large-scale, high-quality, double-blind trials are still needed to determine whether ceftriaxone can safely replace penicillin for the treatment of syphilis when necessary. IMPORTANCE Parenteral penicillin is the first-line regimen for syphilis treatment. However, allergic reactions and poor drug tolerance still present emerging threatening problems with respect to use of this antibiotic. Our results showed a higher serological response rate for ceftriaxone than for penicillin at the 6-month follow-up. Sufficient data are not available for demonstrating significant differences in the efficacy of the other four antibiotics (erythromycin, minocycline, tetracycline, and doxycycline) for treating syphilis. In the clinical treatment of syphilis in patients who are allergic to penicillin or for whom penicillin is not available, ceftriaxone appears to be a better alternative treatment. This meta-analysis provides a reference for clinical treatment of syphilis. Currently, a lack of sufficient evidence to guide antibiotic treatment of syphilis exists, and a need for more high-quality RCTs is still present. This network meta-analysis can lay a foundation for further research.