Early syphilis: serological treatment response to doxycycline/tetracycline versus benzathine penicillin

Benzathine penicillin G is the treatment of choice for syphilis, but doxycycline and tetracycline are effective second-line treatments. The objective of this study was to assess the serological response to treatment for early syphilis with benzathine penicillin compared with doxycycline or tetracycline.

We examined rapid plasma regain (RPR) serological test results of all first-time early syphilis patients in Peking Union Medical College Hospital between 2000 and 2011, comparing treatment with two doses of penicillin to 14-day course of oral doxycycline (100 mg twice daily) or oral tetracycline (500 mg 4 times a day).

Of the 641 early syphilis cases with available treatment outcome data, 606 (94.5%) received penicillin and 35 (5.5%) received doxycycline/tetracycline. More than half (52.1%) had secondary syphilis, 13.4% had primary syphilis, and 34.5% had early latent syphilis. A statistically similar serological treatment success rate (p = 0.157) was observed in penicillin-treated patients 91.4% (554/606), when compared with patients treated with doxycycline/tetracycline 82.9% (29/35).

Doxycycline/tetracycline had a similar serological treatment success rate when compared to penicillin in the treatment of early syphilis.