A retrospective study on nested PCR detection of syphilis treponemes in clinical samples: PCR detection contributes to the diagnosis of syphilis in patients with seronegative and serodiscrepant results

Detection of Treponema pallidum DNA for diagnosis, resistance identification, and treatment outcome prediction in early syphilis among men who have sex with men

OBJECTIVES

We investigated the use of Treponema pallidum DNA (TP-DNA) for diagnosis, resistance identification, and treatment outcome prediction in early syphilis among men who have sex with men (MSM).

METHODS

MSM seeking care for sexually transmitted infections were prospectively enrolled from September 2021 to August 2024. Oral rinse, rectal swab, and urethral swab samples were tested for TP-DNA. Resistance-associated mutations (RAMs) to macrolides and tetracyclines were identified. Treatment responses were compared between syphilis cases with detected TP-DNA and those without.

RESULTS

Of 656 MSM enrolled, TP-DNA was most frequently detected in oral rinse samples (37.8% [193/510]), followed by rectal swab (20.2% [103/510]) and urethral swab samples (11.6%, 59/510) in clinic visits for early syphilis. TP-DNA was detected in 45.7% (233/510) of early syphilis cases and 0.7% (1/141) of cases without syphilis, resulting in a specificity of 99.3% (95%CI, 96.1-100%) and sensitivity 45.7% (95%CI, 41.3-50.1%). Secondary syphilis cases had the highest yield of TP-DNA detection (67.6% [117/173]), followed by primary (48.7% [19/39]) and early latent syphilis cases (32.6% [97/298]). The Ct values of TP-PCR in oral rinse samples were significantly lower in cases of higher rapid plasma reagin (RPR) titers (P<0.001). The rate of T. pallidum harbouring RAMs to macrolides was 58.9% (139/236), increasing over six-month intervals, from 32.4% (12/37) in 2021 to 77.8% (21/27) in 2023. Cases of detected TP-DNA had greater serologic responses to treatments than those without: 80.3% (159/198) vs 67.0% (156/233) at month 6 (P=0.002) and 84.1% (143/170) vs 70.3% (137/195) at month 12 (P=0.002).

CONCLUSIONS

TP-PCR showed high specificity for the diagnosis of early syphilis, which correlated with RPR titers and treatment response, and lower Ct values in oral rinse samples correlated with higher RPR titers. The high prevalence of T. pallidum strains with RAMs to macrolides argues against using azithromycin to treat syphilis in Taiwan.

PCR-detection rates of T. pallidum ssp. pallidum in swab samples from the Czech Republic (2004-2022): Combined RPR, IgM, and PCR tests efficiently detect active syphilis

Syphilis is a multistage sexually transmitted disease caused by Treponema pallidum ssp. pallidum (TPA). This study analyzed clinical samples collected from patients with a diagnosed syphilis infection from 2004-2022, isolated in the Czech Republic. Mucocutaneous swab samples (n = 543) from 543 patients were analyzed, and from these samples, 80.11 % (n = 435) were PCR positive, and 19.89 % (n = 108) were PCR negative for TPA DNA. Swabs were more often positive when collected from syphilis patients in the primary and secondary stages, compared to the latent or unknown stage. There was no significant difference in PCR positivity between the primary and secondary stages (p = 0.099). In IgM-positive patients, a statistically significant association with PCR-positivity was found in samples from seropositive (p = 0.033) and serodiscrepant (RPR negative) patients (p = 0.0006). When assessing our laboratory-defined cases of syphilis, the RPR, IgM, and PCR tests were similarly effective (within the range of 80.1-86.1 %). However, parallel testing with these methods was even more effective, i.e., RPR + PCR was 96.1 % effective and RPR + IgM + PCR was 97.8 % effective. A combination of RPR + PCR, or a combination of all three tests (RPR, IgM, and PCR) can therefore be used to reliably detect active syphilis cases, including reinfections. Our findings show that the reverse algorithm for detecting syphilis could be substantially improved by adding IgM and PCR testing.

Epidemic of multiple Treponema pallidum strains in men who have sex with men in Japan: efficient multi-locus sequence typing scheme and indicator biomarkers

BACKGROUND

The challenges in culturing Treponema pallidum have hindered molecular-biological analysis. This study aims to establish a molecular epidemiological analysis of syphilis among Japanese men who have sex with men (MSM) and to investigate the relationship between bacteremia and associated pathophysiology.

METHODS

We used whole blood specimens from syphilis-diagnosed individuals in Tokyo, collected between February 2019 and June 2022. All individuals were MSM, and most were people with HIV (97.2%). We used a multi-locus sequence typing (MLST) scheme for epidemiological analysis. Sequences for MLST (TP0136, TP0548, and TP0705) were obtained.

RESULTS

Out of 71 whole blood samples, 26 samples (36.6%) were positive for TP0136, and we sequenced three loci for MLST in 22 samples (31.0%). The most frequently detected sequence type (ST) was ST3 (n = 9), followed by ST6 (n = 6). Phylogenetic analysis revealed that 12 samples belonged to the SS14-like group (60%), and 8 samples belonged to the Nichols-like group (40%). Treponema pallidum subsp. endemicum (TEN), the cause of bejel was detected in three samples (12%). There was a significant association between TP0136 detection rate and C- reactive protein (CRP) (77.0% at a cut-off:0.5 mg/dL).

CONCLUSION

Both SS14-like and Nichols-like strains were circulating concurrently, and TEN could have been sexually transmitted among MSM with HIV. Elevated CRP may indicate the presence of the pathogen in the blood.

Serofast status in syphilis: Pathogenesis to therapeutics

Syphilis, a sexually transmitted infection caused by Treponema pallidum, has been experiencing a rise in prevalence in recent years. "Syphilis serofast" describes a unique serological reaction in patients with syphilis whose clinical symptoms have resolved following consistent anti-syphilitic therapy, but the non-Treponema pallidum antigen serologic test is still positive. Syphilis serofast is a risk factor for syphilis recurrence, neurosyphilis, and multisystem involvement. Considering the current lack of comprehensive knowledge about the epidemiological characteristics, pathogenesis, and therapies of syphilis serofast, we conducted an online search of research relating to syphilis serofast over the last twenty years. Previous research has shown that the pathogenesis of syphilis serofast is mainly related to clinical factors, immune factors, syphilis subtypes, and T.pallidum membrane protein repeat gene antigen. There are two distinct viewpoints on the treatment of serofast: no excessive treatment and active treatment. In addition, serofast patients also showed two clinical outcomes: syphilis recurrence and persistent serofast status. This article systematically reviews the related factors, treatment, and clinical outcomes of syphilis serofast, provides a theoretical basis for its research, diagnosis, and treatment, and helps clinicians develop a follow-up treatment management plan for syphilis serofast.

Resurgence of congenital syphilis: new strategies against an old foe

Congenital syphilis is a major global cause of fetal loss, stillbirth, neonatal death, and congenital infection. In 2020, the global rate of congenital syphilis was 425 cases per 100 000 livebirths-substantially higher than WHO's elimination target of 50 cases per 100 000 livebirths. Case rates are rising in many high-income countries, but remain low compared with those in low-income and middle-income settings. This Review aims to summarise the current epidemiology and knowledge on transmission and treatment of syphilis in pregnancy, and proposes measures to reduce the rising incidence seen worldwide. We also describe emerging diagnostic and treatment tools to prevent vertical transmission and improve management of congenital syphilis. Finally, we outline a programme of public health priorities, which include research, clinical, and preventive strategies.

Resurgence of syphilis: focusing on emerging clinical strategies and preclinical models

Syphilis, a sexually transmitted disease (STD) caused by Treponema pallidum (T. pallidum), has had a worldwide resurgence in recent years and remains a public health threat. As such, there has been a great deal of research into clinical strategies for the disease, including diagnostic biomarkers and possible strategies for treatment and prevention. Although serological testing remains the predominant laboratory diagnostic method for syphilis, it is worth noting that investigations pertaining to the DNA of T. pallidum, non-coding RNAs (ncRNAs), chemokines, and metabolites in peripheral blood, cerebrospinal fluid, and other bodily fluids have the potential to offer novel perspectives on the diagnosis of syphilis. In addition, the global spread of antibiotic resistance, such as macrolides and tetracyclines, has posed significant challenges for the treatment of syphilis. Fortunately, there is still no evidence of penicillin resistance. Hence, penicillin is the recommended course of treatment for syphilis, whereas doxycycline, tetracycline, ceftriaxone, and amoxicillin are viable alternative options. In recent years, efforts to discover a vaccine for syphilis have been reignited with better knowledge of the repertoire of T. pallidum outer membrane proteins (OMPs), which are the most probable syphilis vaccine candidates. However, research on therapeutic interventions and vaccine development for human subjects is limited due to practical and ethical considerations. Thus, the preclinical model is ideal for conducting research, and it plays an important role in clinical transformation. Different preclinical models have recently emerged, such as in vitro culture and mouse models, which will lay a solid foundation for clinical treatment and prevention of syphilis. This review aims to provide a comprehensive summary of the most recent syphilis tactics, including detection, drug resistance treatments, vaccine development, and preclinical models in clinical practice.

Penicillin Responsive Presumed Seronegative Ocular Syphilis in a Patient with Human Immunodeficiency Virus: A Case Report and Review of the Literature

Ocular and systemic syphilis are well known to mimic other clinical entities making them challenging to diagnose in many cases. Syphilis testing plays an important role in diagnosis and timely treatment. Here we describe a patient with untreated human immunodeficiency virus (HIV) infection who presented with bilateral panuveitis with repeatedly negative syphilis serologies. In light of worsening retinitis while on aggressive anti-viral treatment and in consideration of the clinical suspicion for syphilitic uveitis, intravenous penicillin was initiated empirically. The patient demonstrated significant improvement subjectively and objectively after treatment. We also review and discuss syphilis testing reliability generally and in HIV co-infected patients in particular. Empiric intravenous penicillin should be considered in patients with clinical features of ocular syphilis despite negative serologic testing, especially in those with HIV co-infection.

Development and clinical validation of a one-step pentaplex real-time reverse transcription PCR assay for detection of hepatitis virus B, C, E, Treponema pallidum, and a human housekeeping gene

BACKGROUND

With the safety of blood transfusion being a major public health concern, the development of a rapid, sensitive, specific, and cost-effective multiplex PCR assay for simultaneous detection of hepatitis B virus(HBV), hepatitis C virus (HCV), hepatitis E virus (HEV), and Treponema pallidum(T. pallidum) in blood is crucial.

METHODS

Five primer pairs and probes were designed towards conserved regions of target genes and used to establish a one-step pentaplex real-time reverse transcription PCR(qRT-PCR) assay for simultaneous detection of HBV, HCV, HEV, T. pallidum, and RNase P(housekeeping gene), providing sample quality check. The clinical performance of the assay was further determined with 2400 blood samples from blood donors and patients in Zhejiang province, and compared the results with commercial singleplex qPCR and serological assays.

RESULTS

The 95% limit of detection(LOD) of HBV, HCV, HEV, and T. pallidum were 7.11 copies/µL, 7.65 copies/µL, 8.45 copies/µL, and 9.06 copies/µL, respectively. Moreover, the assay has good specificity and precision. Compared to the singleplex qPCR assay, the novel assay for detecting HBV, HCV, HEV, and T. pallidum presented 100% clinical sensitivity, specificity, and consistency. Several discrepant results between serological and pentaplex qRT-PCR assays were found. Of 2400 blood samples, there were 2(0.08%) HBsAg positive samples, 3(0.13%) anti-HCV positive samples, 29(1.21%) IgM anti-HEV positive samples and 6(0.25%) anti-T. pallidum positive samples proven negative in nucleic acid detection. 1(0.04%) HBV DNA positive sample and 1(0.04%) HEV RNA positive sample were detected negative by serological testing.

CONCLUSIONS

The developed pentaplex qRT-PCR is the first assay on simultaneous, sensitive, specific, and reproducible detection of HBV, HCV, HEV, T. pallidum, and RNase P in a single tube. It could detect pathogens in blood during the window period of infection and is a good tool for effectively screening blood donors and early clinical diagnosis.

An evaluation of a multiplex PCR assay for the detection of Treponema pallidum, HSV-1, and HSV-2

Multiplex PCR can utilize limited clinical material and is more cost-effective and expected to be used for the detection of Treponema pallidum, herpes simplex virus type 1 and 2 (HSV-1,2). We established a multiplex TP-HSV1-HSV2 Polymerase Chain Reaction (multiplex PCR) targeting the conserved regions of the PolA gene of TP and the UL42 gene of HSV1 and HSV2 to test skin lesions of 115 patients suspected of having TP and HSV1/2 infections. The laboratory sensitivities for all 3 pathogens were 300 copies/mL. The overall clinical sensitivity and specificity in secretion samples for TP were 91.7% and 100%, for HSV1 100% and 98%, and for HSV2 89.7% and 100%, respectively. The method appears superior in patients suspected of early TP infection but negative for nontreponemal antibody testing, and the method is also useful for the differential diagnosis of new skin lesions on genital, perianal, and oral sites of patients with a history of previous syphilis.

Syphilis Diagnosis and Treatment: State of The Art

The present review summarises the current knowledge in the field of syphilis diagnosis and treatment, along with epidemiologic and historical data. A literature search was conducted in PubMed and Google Scholar, using the search terms “syphilis”, “diagnosis”, “dermoscopy”, “management AND treatment”, “laboratory tests AND syphilis”, and “primary OR secondary OR tertiary OR congenital syphilis”. A total of 55 out of 100 papers were included in this review. An overview of the different clinical presentation of primary, secondary, tertiary, and congenital syphilis, with particular attention to dermatologic signs and dermoscopic examination, is provided. The panorama diagnostic procedures are illustrated, along with their accuracy and recommendation. Treatment and management options of patients at different syphilis stages are provided and discussed according to the referring guidelines. The dermatologist can play a key role in providing the early and correct diagnosis and setting up in the proper management of patients with syphilis infection.

Performance characteristics of the SpeeDx PlexPCR VHS assay for the molecular detection of herpes simplex virus, varicella zoster virus, and Treponema pallidum in lesion swabs

This study compares the performance of a commercial polymerase chain reaction (PCR) assay for detection of herpes simplex virus (HSV) 1 and 2, varicella zoster virus (VZV), and Treponema pallidum with laboratory-developed assays. A panel of 250 samples, previously tested using in-house assays, was tested on the PlexPCR® VHS assay. The panel consisted of 202 positive specimens [HSV-1 (n=51); HSV-2 (n=51); VZV (n=51); T. pallidum (n=49)] and 48 negative specimens. Genital samples had been previously tested for HSV-1/2 and T. pallidum and nongenital or unspecified samples for HSV-1/2 and VZV. The overall agreement between the PlexPCR® VHS and in-house assays was 97%. Negative agreement was ≥99%, and positive agreement for individual targets was 96% (47/49) for T. pallidum, 98% for HSV-1 and HSV-2 (50/51), and 100% (51/51) for VZV. Adoption of this assay would allow greater availability of molecular syphilis detection and enhance the diagnostic yield of samples collected from cutaneous/mucocutaneous lesions.