A New Specimen for Syphilis Diagnosis: Evidence by High Loads ofTreponema pallidumDNA in Saliva

Abstract

Background DNA from many pathogens can be detected in saliva. However, the presence and quantity of Treponema pallidum DNA in syphilis patients in saliva is unknown. Methods A total of 234 syphilis patients with different stages and 30 volunteers were enrolled. Paired saliva and plasma samples were collected from all the participants. Consecutive saliva samples from 9 patients were collected every 4 hours following treatment. Treponema pallidum DNA in samples was determined by nested PCR and droplet digital PCR targeting polA and Tpp47. Results Treponema pallidum DNA detection rates in saliva and plasma were 31.0% (9/29) and 51.7% (15/29) in primary syphilis(p=0.11), 87.5% (63/72) and 61.1% (44/72) in secondary syphilis(p<0.001), 25.6%(21/82) and 8.5%(7/82) in latent syphilis (p=0.004), 21.6%(11/51) and 5.9%(3/51) in symptomatic neurosyphilis (p=0.021), respectively. The loads of Tpp47 and polA in saliva were median 627 copies/ml (range, 0-101200 copies/ml) and median 726 copies/ml (range, 0-117260 copies/ml) for syphilis patients, respectively. In plasma, however, the loads of Tpp47 and polA were very low: median 0 copies/ml (range, 0-149.6 copies/ml) and median 0 copies/ml (range, 0-176 copies/ml), respectively. The loads of Treponema pallidum DNA in saliva during treatment were fluctuating downward, and the clearance time was positively correlated with the loads of Treponema pallidum DNA before treatment. Conclusions The collection of saliva is noninvasive and convenient. The high loads of Treponema pallidum DNA in saliva and the reduction after treatment indicated that saliva can be not only a diagnostic fluid for syphilis, but also an indicator of therapeutic effectiveness.

Quantified Detection of Treponema pallidum DNA by PCR Assays in Urine and Plasma of Syphilis Patients

“…Though the diagnosis of syphilis is mainly based on clinical manifestations combined with non- treponema and treponema serological tests, the detection of the nucleic acid of the pathogen from certain specimens is a direct method for the definite diagnosis of infectious diseases. According to previous studies, the detection rates of T. pallidum DNA in secondary syphilis patients reached 87.5 and 64.5% in saliva and oral swabs, respectively ( 4 , 7 ). Blood T. pallidum DNA was positive in suspected primary syphilis patients whose blood rapid plasma regain (RPR) and T. pallidum particle agglutination (TPPA) were nonreactive ( 3 ).…”

“…DNA was dissolved with 100 μL Tris-EDTA (TE) buffer. The presence and loads of polA and Tpp47 genes were measured by nPCR and ddPCR assays, which were performed as described in previous studies ( 3 , 4 ). For nPCR assay, there were 25 and 30 cycles in the first and second rounds of PCR, respectively.…”

“…Known as a multistage sexually transmitted disease, the causative pathogen Treponema pallidum sub. pallidum ( T. pallidum ) can readily disseminate to many organs ( 2 ), and therefore T. pallidum DNA can be detected in various tissues and fluids by PCR assays ( 3 – 6 ).…”

Anal and oral detection ofTreponema pallidumin men who have sex with men with early syphilis infection

“…In this analysis we excluded men with local primary anal lesions and local primary oral lesions with the aim of capturing the pattern of T. pallidum shedding from these sites following systemic dissemination from a remote site of infection. In a recent study of individuals with syphilis by Wang et al , detection of T. pallidum from saliva and blood using droplet digital PCR both peaked during secondary syphilis, providing evidence that T. pallidum is shed from the oral mucosa following systemic dissemination 4. We postulate that T. pallidum may also be shed from the anal region following systemic dissemination; however, this needs to be verified in studies using assays that can detect blood and anal T. pallidum with high sensitivity.…”

“…These findings suggest the secondary stage of syphilis may be the most infectious. Several other recent studies have also found oral detection of T. pallidum to be common during the secondary stage of syphilis; however, none of these studies has also tested all men for concurrent anal T. pallidum 4–6…”