Abstract: 【Abstract】 Objective To investigate the prevalence of and risk factors associated with Neisseria gonorrhoeae （NG）, Chlamydia trachomatis （CT） and high-risk human papillomavirus （HPV） coinfections among patients with newly diagnosed syphilis at a hospital in Nanjing. Methods A cross-sectional study was conducted on patients with newly diagnosed syphilis at the STD Clinic, Hospital of Dermatology, Chinese Academy of Medical Sciences in Nanjing, China from May 2023 to April 2024. Urethral, cervical or rectal swabs were collected according to the gender and types of sexual behavior of the patients. Screening tests for CT, NG and HPV infections were then performed by nucleic acid amplification testing. High-risk HPV testing was performed only in female patients. Univariate analysis was carried out to investigate risk factors associated with CT infection. The chi-square test, chi-square test with continuity correction, or Fisher's exact test was chosen based on the sample size and expected values. Results A total of 111 newly diagnosed syphilis patients with test specimens were collected, including 71 males （64%） and 40 females （36%）, and their ages ranged from 16 to 87 years; there were 82 patients with early syphilis and 29 with late latent syphilis; the number of sexual partners in the past 3 months ranged from 0 to 3. Among the 60 male patients with early syphilis, 1 （1.7%） was co-infected with NG, and 12 （20%） with CT; among the 16 men who have sex with men, 7 （43.8%） were co-infected with CT, while 5 （11.4%） of the 44 heterosexual patients were co-infected with CT, showing a significant difference in CT infection rates between the two groups （χ2 = 5.80, P = 0.016）. Among the 22 female patients with early syphilis, 1 （4.5%） was co-infected with NG, and 8 （36.4%） with CT; among the 12 female patients aged ＜ 25 years, 8 （66.7%） were infected with CT, while none of the 7 patients aged 25－44 years or the 3 patients aged ≥ 45 years were infected with CT, showing a significant difference in CT infection rates among the 3 age groups （P = 0.005）; among the 16 female patients with 1 sexual partner in the past 3 months, 3 were infected with CT, while 5 were infected with CT in the 6 female patients with 2－3 sexual partners in the past 3 months, with a significant difference in CT infection rates between the two groups （P = 0.011）. Out of the 40 female patients with syphilis, 16 （40%） were co-infected with high-risk HPV; the HPV infection rates did not differ among different age groups （age groups of < 25 years, 25－44 years, ≥ 45 years: 8/14, 2/9, 6/17, respectively; P = 0.265）. Conclusion The CT infection rate was relatively high in patients with newly diagnosed early syphilis, and a relatively high infection rate of high-risk HPV was observed in female patients with syphilis aged < 25 years.

Key words: Syphilis, Neisseria gonorrhoeae, Chlamydia trachomatis, Alphapapillomavirus, Coinfection