Use of a Multiplex PCR Assay To Assess the Presence of Treponema pallidum in Mucocutaneous Ulcerations in Patients with Suspected Syphilis

We evaluated the utility of the commercial Allplex genital ulcer realtime PCR multiplex assay for detecting Treponema pallidum, herpes simplex virus 1 (HSV-1) and 2 (HSV-2), and Chlamydia trachomatis serovar L (lymphogranuloma venereum [LGV]) DNA in mucosal and genital ulcers in the context of suspected syphilis. In total, 374 documented genital and mucosal ulcers from patients with and without syphilis presenting at several sexually transmitted infection (STI) centers in France from October 2010 to December 2016 were analyzed at the National Reference Center (CNR) for Bacterial STIs at Cochin Hospital in Paris. T. pailidum subsp. pailidum detection results were compared with the final diagnosis based on a combination of clinical examination, serological results, and in-house nested PCR (nPCR). Detections of HSV and LGV were validated against reference methods. We found that 44.6% of the 374 samples tested were positive for T. pallidum subsp. pallidum, 21% for HSV, and 0.8% for LGV. No positive results were obtained for 30.7% of samples, and 4.8% presented coinfections. For T. pallidum subsp. pallidum detection, the overall sensitivity was 80% (95% confidence interval [Cl], 76.1 to 84.1%), specificity was 98.8% (95% CI, 97.7 to 99.9%), positive predictive value was 98.8% (95% CI, 97.7 to 99.9%) and negative predictive value was 802% (95% CI, 76.2 to 842%), with a rate of concordance with the reference method of 92.5% (k =0.85). This PCR multiplex assay is suitable for T. pallidum subsp. pallidum detection in routine use and facilitates the simultaneous rapid detection of a broad panel of pathogens relevant in a context of suspected syphilis lesions.