Abstract: Objective To analyze the epidemiology, clinical data and laboratory results of patients with serofast of syphilis, and explore the related factors of serofast of syphilis. Method According to the standards formulated by the "Expert consensus on the clinical treatment of syphilis serofast" in 2015, a structured questionnaire survey was conducted on the patients who were diagnosed with syphilis serofast in the dermatology department of center for chronic disease prevention of Shenzhen from January 2018 to December 2021. The investigation items included ①The demographic characteristics, life behavior characteristics, history of sexually transmitted diseases and other clinical data were collected. ②Blood was collected for treponema pallidum particle agglutination test (TPPA), syphilis toluidine red unheated serum test (TRUST), and cerebrospinal fluid was collected for leukocyte count and other test indexes of cerebrospinal fluid. Epidata 3.1 was used for data double entry and consistency test. Result Among the 100 patients with serofast of syphilis, there were 37 males and 63 females. There were 4 patients with primary syphilis (4.0%), 19 patients with secondary syphilis (19.0%) and 77 patients with latent syphilis (77.0%). The patients aged from 31 to 40 years old were the most. The baseline titer of toluidine red unheated serum test (TRUST) in 88 patients was 1:256~1:1. The most patients with TRUST baseline titer ≤1:8, accounting for 51%. After treatment, 89 patients had TRUST titer maintained at 1:8~1:1, and 11 patients had TRUST titer above 1:8. There was significant difference between the baseline TRUST titer and the current titer of serofast sate (P<0.01). Of the 100 patients treated for the first time, 97 were treated with penicillin. 57 patients were retreated once due to serofast sate, of which 55 cases were still treated with penicillin and 2 cases were treated with doxycycline. The serum titer still did not turn negative after treatment. Among the 100 patients, 63 patients had cerebrospinal fluid laboratory examination, of which 3 patients were patients with neurosyphilis. Serofast sate occurred after treatment, and 60 patients had no abnormality in cerebrospinal fluid examination. Conclusion Women, latent syphilis and low baseline titer are more prone to serofast state. Benzathine penicillin can still cause serofast of syphilis in the treatment of syphilis. The curative effect of benzathine penicillin in the treatment of serofast is not ideal. New therapeutic drugs should be developed to reduce the occurrence of serofast and treat serofast of syphilis.

Key words: Syphilis, Serofast, Clinical analysis, Epidemiology