Azithromycin treatment failure among primary and secondary syphilis patients in Shanghai

Azithromycin has been used to treat primary and secondary syphilis and as prophylaxis for sexual partners. We evaluated syphilis treatment failure in patients who received azithromycin therapy.

Patients who did not respond to azithromycin therapy were referred to Shanghai Skin Disease and sexually transmitted disease hospital. Treatment failure was defined as follows: (1) persistent ulcers or cutaneous or mucosal lesions 1 month after therapy; or (2) detection of spirochetes in dark-field microscopy examination of a lesion at least 1 week after treatment; or (3) failure of rapid plasma reagin titers to decrease 4-fold at 3 months after treatment.

A total of 132 patients with primary and secondary syphilis who failed azithromycin therapy were referred to our hospital between January 2001 and October 2008. Of 132 patients, 42 (31.8%) had primary syphilis and 90 (68.2%) had secondary syphilis. Twenty-six patients with primary syphilis developed multiple lesions or secondary syphilis, or persistent ulcers despite using azithromycin. The skin or mucosal lesions did not resolve in 37 patients with secondary syphilis after azithromycin treatment. Ten patients had a positive dark-field examination for Treponema pallidum (T. pallidum) after treatment. The serum rapid plasma reagin titers studied in all cases had failed to decrease 4-fold at 3 months after therapy. The doses of azithromycin used for treatment ranged from 4 to 30 g.

The failure of azithromycin to cure a substantial number of patients with primary and secondary syphilis in Shanghai suggests that azithromycin has limited therapeutic value in this setting.