Molecular Characterization of Genital and Extragenital Lesions With the PlexPCR VHS Assay in Patients Diagnosed With Syphilis

Background. Syphilis diagnosis relies on immunologic markers and clinical protocols. However, syphilitic lesions can be confused with other genital ulcer diseases. Methods. Using a PlexPCR VHS assay, we analyzed lesion DNA samples from 87 individuals who were clinically diagnosed with early syphilis infection and had at least 1 positive serologic test result. DNA was detected by the PlexPCR VHS multiplex assay and β-globin genes. Results. Among the participants, 99% (86/87) had a positive rapid treponemal test result. DNA was successfully detected in 91% (79/87) of the lesion samples. PlexPCR VHS identified 5 herpes simplex virus (HSV)/Treponema pallidum coinfections (2 HSV-1 and 3 HSV-2), only T pallidum DNA in 62% (49/79), and only HSV-2 in 12.7% (10/79). While 19% (15/79) were negative for all pathogens, none were varicella zoster virus positive. The PlexPCR VHS had 68.4% agreement with the clinical diagnosis. Conclusions. Since the PlexPCR VHS detects multiple organisms simultaneously, it can help to confirm actual syphilis and identify other pathogen coinfections or the pathogen causing the ulcer.