Recent studies have shown that Treponema pallidum can be detected from asymptomatic oral and anal sites by PCR in individuals with early syphilis. This study aimed to investigate T. pallidum PCR testing of oral, anal and vaginal sites among individuals reporting sexual contact with a partner with syphilis.
Methods
This was a prospective, cross-sectional study of men and women who reported sexual contact with a partner with syphilis at the Melbourne Sexual Health Centre, Australia, from November 2018 to March 2020. All individuals had an oral rinse and oral swab collected for PCR. Additionally, MSM had an anal swab and women had a vaginal swab for PCR regardless of the presence of lesions. Any mucocutaneous lesions at other sites were also swabbed for PCR. Syphilis serology was performed.
Results
407 individuals (364 MSM, 22 heterosexual men, 21 women) provided 398 oral rinses, 363 oral swabs, 351 anal swabs, and 19 vaginal swabs. 42 contacts (10%) were diagnosed with early syphilis based on positive serology and/or positive PCR. Of these, 19 (45%) tested positive by PCR from any anatomical site, with all having positive serology. Among these 19 cases, there were 4 women and 5 men without symptoms or signs of syphilis (Table 1). Of the 4 women, 3 tested positive by PCR from the vagina with no vaginal symptoms and 3 had no prior serology. Of the 5 men, 3 tested positive by PCR from the anus with no anal symptoms. Five (2 women and 3 men) tested positive by PCR in the oral cavity with no oral symptoms. PCR detection at multiple sites occurred in one woman and one MSM.
Conclusion
T. pallidum was detected at oral, anal and vaginal sites in the absence of symptoms at these sites among sexual contacts of syphilis.The asymptomatic PCR detection indicated early latent syphilis infection among the individuals, who would have been otherwise diagnosed with latent syphilis of unknown duration in some cases. The change in staging resulted in shortening the duration of treatment required from three injections given one week apart to single dose therapy.
