Efficacy of minocycline in the treatment of early syphilis.

Syphilis is the third prevalent infectious disease in China, caused by the spirochete bacterium Treponema pallidum. Minocycline is a derivative of tetracycline used as an alternative treatment for syphilis, but there are few studies in this field. In this research, we compared the efficacy of benzathine penicillin and minocycline in the treatment of early syphilis patients and analyzed some of the factors affecting the efficacy of minocycline. A total of 276 eligible patients treated between January 2011 and December 2017 were retrospectively analyzed, and 158 patients received 100 mg of minocycline orally, twice daily for 28 days, while 118 patients received benzathine penicillin, 2.4 million units intramuscular injections, once a week, 1-2 times in all. All patients accepted rapid plasma regain (RPR) serological tests and followed up for 24 months to evaluate serological treatment responses. After comparison, the serological cure rate of the minocycline treatment group (85.44%) was similar to the benzathine penicillin treatment group (88.14%). Besides, patients in the minocycline treatment group with higher initial RPR titer (≥1:32) exhibited better treatment effect. In addition, during the 24-month follow-up, the serological cure rate of primary syphilis patients after minocycline treatment was significantly higher than that of secondary and early latent syphilis patients. Therefore, minocycline may be an effective alternative treatment to early syphilis when benzathine penicillin is not available.