Molecular Typing of Treponema pallidum in Denmark: A Nationwide Study of Syphilis

BASHH UK guidelines for the management of syphilis 2024

The 2024 UK guidelines for the management of syphilis are in line with current evidence and practice within the UK. Key updates are detailed at the start of the article. These guidelines are accompanied by the first UK guidelines for the management of syphilis in pregnant people and children, 2024.

Typing of Treponema pallidum in a Brazilian sample and follow-up of treatment using molecular assays

Syphilis remains a significant public health concern, with serological assays being the primary method for diagnosis. However, molecular techniques have proven to be reliable tools for the diagnosis and understanding of the transmission dynamics of Treponema pallidum infection. This study aimed to evaluate the efficacy of syphilis treatment using molecular assays, perform Enhanced Centers for Disease Control and Prevention (ECDC) typing, and analyze resistance (macrolide and doxycycline) in the T. pallidum isolate. PCR assay amplified treponemal DNA only from the lesion sample, whereas qPCR was able to amplify DNA in both lesion and blood samples before treatment. Throughout the treatment follow-up, qPCR effectively did not identify treponemal DNA in the blood for up to one to two weeks after treatment. ECDC typing revealed the genotype 14 e/g in the Brazilian T. pallidum isolate, and the presence of the A2058G mutation in 23 S rRNA gene, indicating macrolide resistance. Although, the G1058C mutation in 16 S rRNA gene was not detected. Notably, qPCR demonstrated its potential for diagnosing T. pallidum in blood samples, even when the treponemal DNA levels were low, enabling more accurate and sensitive diagnosis and guiding better syphilis therapy. In addition, to the best of our knowledge, this study represents the first identification of subtype 14 e/g and azithromycin resistance in a Brazilian T. pallidum isolate.

Analysis of molecular subtypes and antibiotic resistance in Treponema pallidum isolates from blood donors in Khyber Pakhtunkhwa, Pakistan

Syphilis, caused by Treponema pallidum, is resurging globally. Molecular typing allows for the investigation of its epidemiology. In Pakistan and other nations, T. pallidum subsp. pallidum has developed widespread macrolide resistance in the past decade. A study at the Peshawar Regional Blood Centre from June 2020-June 2021 analyzed serum samples from 32,812 blood donors in Khyber Pakhtunkhwa, Pakistan, to assess circulating T. pallidum strains and antibiotic resistance. Blood samples were initially screened for T. pallidum antibodies using a chemiluminescent microparticle immunoassay (CMIA). CMIA-reactive samples underwent polymerase chain reaction (PCR) targeted the polA, tpp47, bmp, and tp0319 genes. PCR-positive samples were further analyzed for molecular subtyping using a CDC-developed procedure and tp0548 gene examination. All PCR-positive samples were analyzed for the presence of point mutations A2058G and A2059G in 23S rRNA, as well as the G1058C mutation in 16S rRNA. These mutations are known to impart antimicrobial resistance to macrolides and doxycycline, respectively. Out of 32,812 serum samples, 272 (0.83%) were CMIA-reactive, with 46 being PCR-positive. Nine T. pallidum subtypes were identified, predominantly 14d/f. The A2058G mutation in 23S rRNA was found in 78% of cases, while G1058C in 16S rRNA and A2059G in 23S rRNA were absent. The research found donor blood useful for assessing T. pallidum molecular subtypes and antibiotic resistance, especially when chancres are not present. The prevalent subtype was 14d/f (51.85%), and the high macrolide resistance of 36 (78%) indicates caution in using macrolides for syphilis treatment in Khyber Pakhtunkhwa, Pakistan.

Prognostic effect of HIV on visual acuity in ocular syphilis: a systematic review

BACKGROUND/OBJECTIVES

Ocular syphilis is a vision-threatening disease that can lead to permanent blindness if left untreated. The global re-emergence of syphilis warrants greater investigations into the visual prognosis of eyes affected by this potentially devastating disease. This systematic review investigates the impact of HIV on visual acuity (VA) outcomes in ocular syphilis.

METHODS

A literature search of Medline, PubMed, Embase, Clinicaltrials.gov and Cochrane Reviews was conducted for studies published between 01 January 2011 and 19 March 2022, reporting non-aggregate initial and post-treatment VA data of eyes with ocular syphilis and corresponding HIV status in patients ≥ 18 years.

RESULTS

A total of 95 studies, including 364 patients and 568 eyes, were evaluated. Among people living with HIV with a diagnosis of ocular syphilis, affected eyes were more likely to have optic nerve involvement and panuveitis. However, HIV status, CD4 cell count, and HIV viral load were not predictive of VA outcomes of treated ocular syphilis. Prognostic factors of final VA worse than 1.00 logMAR were female sex, the presence of macular edema, and VA ≥ 1.00 at presentation. The strongest predictor of a worse final VA was VA ≥ 1.00 at presentation.

CONCLUSIONS

This systematic review demonstrates that HIV status, CD4 cell count, and HIV viral load are not significant factors impacting VA outcomes of eyes with ocular syphilis. While visual prognosis is generally good, poor visual outcome is most strongly predicted by poor VA at presentation. This underscores the importance of early recognition and treatment prior to permanent vision loss.

A Comparison of Treponema pallidum Subspecies pallidum Molecular Typing Systems: Multilocus Sequence Typing vs. Enhanced Centers for Disease Control and Prevention Typing

BACKGROUND

At least 3 syphilis typing systems are proposed. Recent work suggests that multilocus sequence typing (MLST) may be superior to enhanced Centers for Disease Control and Prevention typing (ECDCT) by yielding a higher discriminatory power. The goal of this study was to compare the 2 systems and identify associations between neurosyphilis and strain types.

METHODS

Multilocus sequence typing for tp0136, tp0548, and tp0705 was determined for DNA from 78 Treponema pallidum subspecies pallidum isolates propagated in rabbits, 10 oral and 10 genital or non-genital lesion swabs, and 10 blood samples from patients with syphilis. These samples were chosen because they were completely typeable by ECDCT. Using both systems, association between strain types and neurosyphilis, defined as a reactive cerebrospinal fluid Venereal Disease Research Laboratory test, was determined. Partial and complete ECDCT types were also determined for samples from different anatomical sites in 35 patients, and from blood and blood isolates (rabbit propagated) from 13 patients.

RESULTS

The MLST type could be fully determined for 100 (92.6%) of 108 samples. Although MLST subdivided 3 common ECDCT types, it failed to distinguish among others. Neurosyphilis was more common in individuals infected with type 1.1.2 and tp0705 type 2 using MLST, and tp0548 type f using ECDCT. Enhanced Centers for Disease Control and Prevention typing was stable among anatomical sites and between patient-derived and rabbit propagated organisms.

CONCLUSIONS

Compared with ECDCT, MLST was not uniformly more discriminating. Both typing systems demonstrate that specific types may be more neurotropic than others.

Enhanced molecular typing and macrolide and tetracycline-resistance mutations of Treponema pallidum in Barcelona

Aim: To describe the molecular types of Treponema pallidum and the proportion of macrolide and tetracycline resistance mutations in Barcelona. Materials & methods: Molecular type was determined using the Enhanced-CDC Typing system and antibiotic resistance was determined by sequencing the 23S and 16S rRNA genes. Results: A total of 183 patients were enrolled and 213 specimens (99 ulcers, 114 bloods) were collected. Sixty-two (70.5%) of 88 ulcers and 0 (0%) of bloods T. pallidum-DNA containing samples were fully typed. Up to 21 different strain types were identified (14d/g in 27.4%; 14f/g in 14.5%). Macrolide resistance mutations were present in 95% and tetracycline in 0%. Conclusion: Several different strains co-exist in Barcelona with a high proportion of macrolide resistance and absence of tetracycline resistance.

A comparison of genotyping tool in Treponema pallidum: Review and meta-analysis

BACKGROUND

To decipher the molecular epidemiology of the Treponema pallidum subspecies, pallidum, researchers have developed different molecular typing schemes which identify strains type from clinical specimens. However, the results of these studies show remarkable diversity.

METHODS

We searched for literature in PubMed, MEDLINE, Web of Sciences, and OVID from January 1998 to January 2019, in order to compare the efficiency of typing schemes using published evidence for systematic reviews and meta-analyses.

RESULTS

From the 43 studies included, the overall typing efficiency of Treponema pallidum was 71.4% (95% CI: 63.2-78.9%). Subgroup analyses indicated that the typing efficiency of CDC-typing (CDCT, 68.2%, 95% CI: 53.6-81.2%) was worse than those of enhanced CDC-typing (ECDCT, 72.3%, 95% CI: 60-83.1%), CDC-rspA (81.6%, 95% CI: 76.1-86.6%), multi-locus sequence typing (MLST, 67.1%, 95% CI: 61.1-72.7), and sequencing-based molecular typing (SBMT, 71.6%, 95% CI: 50-89.2%). A limitation of this review is that the studies included employed different criteria to collect and investigate samples of Treponema pallidum, which could contribute to heterogeneity.

CONCLUSIONS

This analysis suggests that CDCT is an inferior scheme in molecular typing, the discriminatory power was very similar for ECDCT and SBMT. Other factors contributing to the heterogeneity between typing studies warrants further study.

Strain diversity of Treponema pallidum subsp. pertenue suggests rare interspecies transmission in African nonhuman primates

In our most recent study, we found that in Tanzania infection with Treponema pallidum (TP) subsp. pertenue (TPE) is present in four different monkey species. In order to gain information on the diversity and epidemiological spread of the infection in Tanzanian nonhuman primates (NHP), we identified two suitable candidate genes for multi-locus sequence typing (MLST). We demonstrate the functionality of the MLST system in invasively and non-invasively collected samples. While we were not able to demonstrate frequent interspecies transmission of TPE in Tanzanian monkeys, our results show a clustering of TPE strains according to geography and not host species, which is suggestive for rare transmission events between different NHP species. In addition to the geographic stability, we describe the relative temporal stability of the strains infecting NHPs and identified multi-strain infection. Differences between TPE strains of NHP and human origin are highlighted. Our results show that antibiotic resistance does not occur in Tanzanian TPE strains of NHP origin.

Early syphilis: risk factors and clinical manifestations focusing on HIV-positive patients

BACKGROUND

Since 2000, substantial increases in syphilis in men who have sex with men (MSM) have been reported in many cities. Condomless anal sex (CAS) is one of the factors, along with drugs for sex and sex in group. This study identified factors and clinical manifestations as well as Treponema pallidum (T.pallidum) strains that could be related to early syphilis in Barcelona.

METHODS

This prospective study was conducted in a sexually transmitted infections unit in 2015. Epidemiological, behavioral, clinical and microbiological variables were collected in a structured form. Univariate and multivariate statistical analyses were performed focusing on HIV-positive patients.

RESULTS

Overall, 274 cases were classified as having early syphilis (27.5% primary, 51.3% secondary, and 21.2% early latent syphilis). In all, 94% of participants were MSM and 36.3% were HIV-positive. The median number of sexual contacts in the last 12 months was 10; 72.5% practiced CAS, 50.6% had sex in group, and 54.7% consumed drugs. HIV-positive cases had more anonymous sex contacts (p = 0.041), CAS (p = 0.002), sex in group (p < 0.001) and drugs for sex (p < 0.001). In the multivariate analysis, previous syphilis (adjusted odds ratio [aOR] 4.81 [2.88-8.15]), previous Neisseria gonorrhoeae infection (aOR 3.8 [2.28-6.43]), and serosorting (aOR 20.4 [7.99-60.96]) were associated with having syphilis. Clinically, multiple chancres were present in 31% of cases with no differences on serostatus, but anal chancre was most common in HIV-positive patients (p = 0.049). Molecular typing did not conclusively explain clinical presentation in relation to specific T.pallidum strains.

CONCLUSION

Control of syphilis remains a challenge. Similar to prior studies, HIV-positive patients were found to engage more often in sexual behaviors associated with syphilis than HIV-negative patients. Clinical manifestations were rather similar in both groups, although anal chancre was most common in HIV-positive patients. Various strain types of syphilis were found, but no clinical associations were identified.

Cerebral Syphilitic Gumma Can Arise Within Months of Reinfection: A Case of Histologically Proven Treponema pallidum Strain Type 14b/f Infection With Human Immunodeficiency Virus Positivity

A 44-year-old man with human immunodeficiency virus positivity developed cerebral gumma 6 months after appropriate therapy for secondary syphilis. It was surgically resected and histologically, Treponema pallidum (14b/f, a relatively rare strain type) was proven. A complete set of modern techniques was performed to depict rare complication of this classic disease.

Sequencing of Treponema pallidum subsp. pallidum from isolate UZ1974 using Anti-Treponemal Antibodies Enrichment: First complete whole genome sequence obtained directly from human clinical material

Treponema pallidum subsp. pallidum (TPA) is the infectious agent of syphilis, a disease that infects more than 5 million people annually. Since TPA is an uncultivable bacterium, most of the information on TPA genetics comes from genome sequencing and molecular typing studies. This study presents the first complete TPA genome (without sequencing gaps) of clinical isolate (UZ1974), which was obtained directly from clinical material, without multiplication in rabbits. Whole genome sequencing was performed using a newly developed Anti-Treponemal Antibody Enrichment technique combined with previously reported Pooled Segment Genome Sequencing. We identified the UW074B genome, isolated from a sample previously propagated in rabbits, to be the closest relative of the UZ1974 genome and calculated the TPA mutation rate as 2.8 x 10(-10) per site per generation.

Genetics of human and animal uncultivable treponemal pathogens

Treponema pallidum is an uncultivable bacterium and the causative agent of syphilis (subsp. pallidum [TPA]), human yaws (subsp. pertenue [TPE]), and bejel (subsp. endemicum). Several species of nonhuman primates in Africa are infected by treponemes genetically undistinguishable from known human TPE strains. Besides Treponema pallidum, the equally uncultivable Treponema carateum causes pinta in humans. In lagomorphs, Treponema paraluisleporidarum ecovar Cuniculus and ecovar Lepus are the causative agents of rabbit and hare syphilis, respectively. All uncultivable pathogenic treponemes harbor a relatively small chromosome (1.1334-1.1405 Mbp) and show gene synteny with minimal genetic differences (>98% identity at the DNA level) between subspecies and species. While uncultivable pathogenic treponemes contain a highly conserved core genome, there are a number of highly variable and/or recombinant chromosomal loci. This is also reflected in the occurrence of intrastrain heterogeneity (genetic diversity within an infecting bacterial population). Molecular differences at several different chromosomal loci identified among TPA strains or isolates have been used for molecular typing and the epidemiological characterization of syphilis isolates. This review summarizes genome structure of uncultivable pathogenic treponemes including genetically variable regions.

Molecular Typing of Syphilis-Causing Strains Among Human Immunodeficiency Virus-Positive Patients in Antwerp, Belgium

Centers for Disease Control and Prevention and sequencing-based treponeme typing was used to analyze 72 blood samples, collected from human immunodeficiency virus and syphilis co-infected patients during 2014 to 2015 in Antwerp, Belgium. Twenty-nine (40.3%) isolates were polymerase chain reaction positive for Treponema pallidum, and all tested were macrolide-resistant. Four genotypes were identified by sequencing-based typing including two new genotypes, U4NR8 and SU9R8, whereas enhanced Centers for Disease Control and Prevention typing revealed 7 subtypes.

Development of a Multilocus Sequence Typing (MLST) scheme for Treponema pallidum subsp. pertenue: Application to yaws in Lihir Island, Papua New Guinea

BACKGROUND

Yaws is a neglected tropical disease, caused by Treponema pallidum subsp. pertenue. The disease causes chronic lesions, primarily in young children living in remote villages in tropical climates. As part of a global yaws eradication campaign initiated by the World Health Organization, we sought to develop and evaluate a molecular typing method to distinguish different strains of T. pallidum subsp. pertenue for disease control and epidemiological purposes.

METHODS AND PRINCIPAL FINDINGS

Published genome sequences of strains of T. pallidum subsp. pertenue and pallidum were compared to identify polymorphic genetic loci among the strains. DNA from a number of existing historical Treponema isolates, as well as a subset of samples from yaws patients collected in Lihir Island, Papua New Guinea, were analyzed using these targets. From these data, three genes (tp0548, tp0136 and tp0326) were ultimately selected to give a high discriminating capability among the T. pallidum subsp. pertenue samples tested. Intragenic regions of these three target genes were then selected to enhance the discriminating capability of the typing scheme using short readily amplifiable loci. This 3-gene multilocus sequence typing (MLST) method was applied to existing historical human yaws strains, the Fribourg-Blanc simian isolate, and DNA from 194 lesion swabs from yaws patients on Lihir Island, Papua New Guinea. Among all samples tested, fourteen molecular types were identified, seven of which were found in patient samples and seven among historical isolates or DNA. Three types (JG8, TD6, and SE7) were predominant on Lihir Island.

CONCLUSIONS

This MLST approach allows molecular typing and differentiation of yaws strains. This method could be a useful tool to complement epidemiological studies in regions where T. pallidum subsp. pertenue is prevalent with the overall goals of improving our understanding of yaws transmission dynamics and helping the yaws eradication campaign to succeed.

Immunogenicity and immunoreactivity of Tp0821 recombinant protein from Treponema pallidum

Treponema pallidum (Tp) is responsible for invading reproductive organs and the skin in early stages, and involves almost all organs/systems at advanced stages. In the present study, screening of the dominant epitope fragment of the Tp outer membrane protein, Tp0821, was performed and the prokaryotic expression vector pQE32/Tp0821 was constructed. The denaturation and dialysis of rTp0821 were achieved through ultrasound, inclusion body washing and dissolution. Experiments in purified rTp0821‑immune New Zealand rabbits indicated that the recombinant proteins were of high immunogenicity, and the irritation led a marked humoral immune response in the New Zealand rabbits. Western blot analysis showed that the purified recombinant proteins reacted with the Tp‑positive infected serum, confirming the high level of immunoreactivity. The delayed type hypersensitivity of rTp0821 recombinant proteins was positive, indicating that rTp0821 induced a specific cell immune response and was selected as a Tp vaccine candidate protein. The findings of the present study provided novel evidence, which provided information for further investigations on the pathogenic mechanism of Tp and the development of diagnostic reagents.

Molecular typing of Treponema pallidum isolates from Buenos Aires, Argentina: Frequent Nichols-like isolates and low levels of macrolide resistance

A total of 54 clinical samples, including genital lesion swabs, whole blood and cerebrospinal fluid from patients diagnosed with syphilis were collected in 2006 and in 2013 in Buenos Aires, Argentina. Treponemal DNA was detected in 43 of the analyzed samples (79.6%) and further analyzed using Sequencing-based molecular typing (SBMT) and Enhanced CDC-typing (ECDCT). By SBMT, 10 different Treponema pallidum subsp. pallidum (TPA) genotypes were found, of which six were related to the TPA SS14 strain, and four to the TPA Nichols strain. The 23S rRNA gene was amplified in samples isolated from 42 patients, and in six of them (14.3%), either the A2058G (four patients, 9.5%) or the A2059G (two patients, 4.8%) mutations were found. In addition to Taiwan, Madagascar and Peru, Argentina is another country where the prevalence of Nichols-like isolates (26.8%) is greater than 10%.

Treponema pallidum Strain Types and Association with Macrolide Resistance in Sydney, Australia: New TP0548 Gene Types Identified

Strain typing of Treponema pallidum, using the three-target enhanced classification scheme, was performed with 191 samples obtained between 2004 and 2011 in Sydney, Australia. The most common strain type was 14d/g (92/191 samples [48%]). Two new TP0548 gene types were detected (m and n). Strain type was associated with macrolide resistance and possible acquisition outside Australia.