(P400) Multiplex PCR testing of anogenital lesions for Treponema pallidum and herpes simplex virus in primary care improves the detection of primary syphilis.

Background: Syphilis epidemics are worsening in many countries and earlier diagnosis is needed to reduce infectiousness and transmission. Better detection of primary syphilis is needed in primary care settings as this is where many syphilis cases present. The aim of this study was to evaluate whether the use of multiplex PCR testing of anogenital lesions for Treponema pallidum and herpes simplex virus (HSV) in general practice improves the detection of primary syphilis.



Methods: Between September and December 2022, multiplex PlexPCR VHS (SpeeDx) testing for T. pallidum and HSV type-1 and -2 was performed on all clinical specimens received from general practitioners across Victoria using the Melbourne Pathology laboratory network if HSV PCR testing of anogenital lesions was requested in a patient aged ≥18, even if T. pallidum PCR was not requested. Multiplex PCR was also performed if testing for other STIs or T. pallidum PCR was requested. Clinics were made aware of this testing via a letter that included a link to an educational video on PCR testing for syphilis.



Results: During the period,1,291 multiplex tests were performed, 882 in women and 398 in men, 18 of which were positive for T. pallidum. Of the positive T. pallidum samples, 6/18 (33%) (95%CI: 13-59%) were from patients where the practitioner had requested PCR for HSV but not T. pallidum: 2 female and 4 male. All 6 cases were negative for HSV on PCR. Among the 2 females, both swabs were from genital sites. Among the 4 males, 3 swabs were genital and one anal. Four individuals (2 women, 2 men) resided in more socioeconomically disadvantaged areas known to have higher rates of syphilis in women of reproductive age.



Conclusion: Multiplex PCR testing for syphilis and herpes in primary care resulted in the detection of primary syphilis in male and female patients which may have otherwise not been identified. This is likely to have led to earlier diagnosis and treatment, potentially reducing infectiousness and progression of infection.