Molecular typing of Treponema pallidum: a systematic review and meta-analysis

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.

Neurosyphilis: insights into its pathogenesis, susceptibility, diagnosis, treatment, and prevention

Background and aim

Invasion of the central nervous system by Treponema pallidum can occur at any stage of syphilis. In the event that T. pallidum is not cleared promptly, certain individuals may experience progression to neurosyphilis, which manifests as cognitive and behavioral abnormalities, limb paralysis, and potentially fatal outcomes. Early identification or prevention of neurosyphilis is therefore crucial. The aim of this paper is to conduct a critical and narrative review of the latest information focusing exclusively to the pathogenesis and clinical management of neurosyphilis.

Methodology

To compile this review, we have conducted electronic literature searches from the PubMed database relating to neurosyphilis. Priority was given to studies published from the past 10 years (from 2013 to 2023) and other studies if they were of significant importance (from 1985 to 2012), including whole genome sequencing results, cell structure of T. pallidum, history of genotyping, and other related topics. These studies are classic or reflect a developmental process.

Results

Neurosyphilis has garnered global attention, yet susceptibility to and the pathogenesis of this condition remain under investigation. Cerebrospinal fluid examination plays an important role in the diagnosis of neurosyphilis, but lacks the gold standard. Intravenous aqueous crystalline penicillin G continues to be the recommended therapeutic approach for neurosyphilis. Considering its sustained prominence, it is imperative to develop novel public health tactics in order to manage the resurgence of neurosyphilis.

Conclusion

This review gives an updated narrative description of neurosyphilis with special emphasis on its pathogenesis, susceptibility, diagnosis, treatment, and prevention.

Low genetic diversity of Treponema pallidum ssp. pertenue (TPE) isolated from patients' ulcers in Namatanai District of Papua New Guinea: Local human population is infected by three TPE genotypes

Yaws is an endemic disease caused by Treponema pallidum subsp. pertenue (TPE) that primarily affects children in rural regions of the tropics. The endemic character of yaws infections and the expected exclusive reservoir of TPE in humans opened a new opportunity to start a yaws eradication campaign. We have developed a multi-locus sequence typing (MLST) scheme for TPE isolates combining the previously published (TP0548, TP0488) and new (TP0858) chromosomal loci, and we compared this typing scheme to the two previously published MLST schemes. We applied this scheme to TPE-containing clinical isolates obtained during a mass drug administration study performed in the Namatanai District of Papua New Guinea between June 2018 and December 2019. Of 1081 samples collected, 302 (28.5%) tested positive for TPE DNA, from which 255 (84.4%) were fully typed. The TPE PCR-positivity in swab samples was higher in younger patients, patients with single ulcers, first ulcer episodes, and with ulcer duration less than six months. Non-treponemal serological test positivity correlated better with PCR positivity compared to treponema-specific serological tests. The MLST revealed a low level of genetic diversity among infecting TPE isolates, represented by just three distinct genotypes (JE11, SE22, and TE13). Two previously used typing schemes revealed similar typing resolutions. Two new alleles (one in TP0858 and one in TP0136) were shown to arise by intragenomic recombination/deletion events. Compared to samples genotyped as JE11, the minor genotypes (TE13 and SE22) were more frequently detected in samples from patients with two or more ulcers and patients with higher values of specific TP serological tests. Moreover, the A2058G mutation in the 23S rRNA genes of three JE11 isolates was found, resulting in azithromycin resistance.

A Cluster of Ocular Syphilis Cases with a Common Sex Partner - Southwest Michigan, 2022

Untreated syphilis can lead to ocular syphilis, otosyphilis, and neurosyphilis, conditions resulting from Treponema pallidum infection of the eye, inner ear, or central nervous system. During March-July 2022, Michigan public health officials identified a cluster of ocular syphilis cases. The public health response included case investigation, partner notification, dissemination of health alerts, patient referral to a public health clinic for diagnosis and treatment, hospital care coordination, and specimen collection for T. pallidum molecular typing. Five cases occurred among southwest Michigan women, all of whom had the same male sex partner. The women were aged 40-60 years, HIV-negative, and identified as non-Hispanic White race; the disease was staged as early syphilis, and all patients were hospitalized and treated with intravenous penicillin. The common male sex partner was determined to have early latent syphilis and never developed ocular syphilis. No additional transmission was identified after the common male partner's treatment. Due to lack of genetic material in limited specimens, syphilis molecular typing was not possible. A common heterosexual partner in an ocular syphilis cluster has not been previously documented and suggests that an unidentified strain of T. pallidum might have been associated with increased risk for systemic manifestations of syphilis. A high index of clinical suspicion and thorough sexual history are critical to diagnosing ocular syphilis, otosyphilis, and neurosyphilis. Coordination of disease surveillance with disease intervention specialist investigation and treatment referral can interrupt syphilis transmission.

Molecular Detection and Typing of Treponema pallidum in Non-Ocular Samples from Patients with Ocular Syphilis

INTRODUCTION

Ocular syphilis is a rare but potentially sight-threatening manifestation of infection with the spirochete Treponema pallidum subspecies pallidum. Molecular strain typing of clinical specimens obtained from patients with syphilis can provide useful epidemiological and clinical information. In this study, we assess the utility of non-ocular clinical samples in strain typing for patients with diagnosed ocular syphilis.

METHODS

We collected samples of excess blood, serum, and cerebrospinal fluid (CSF) from 6 patients with ocular syphilis treated in 2013-2016. DNA was extracted, purified, and then analyzed using an enhanced molecular typing method including sequence analysis of tp0548, number of repeats in the arp gene, and restriction fragment length polymorphism of the tpr gene.

RESULTS

Molecular strain typing based on tp0548 gene sequence analysis revealed two cases of type F and two cases of type G in 3 of 6 (50%) cases with CSF samples, 1 of which was obtained after starting antibiotics. In a patient with 2 distinct episodes, the same tp0548 type (type G) was identified in both episodes using different sample types (CSF, whole blood). Serum samples were available in 6 cases, but none were successfully typed with any of the methods. Amplification of the tpr and arp genes was unsuccessful in all cases. Overall, strain types were identified in 4 of the 7 episodes.

CONCLUSION

Treponema pallidum strain types F and G were detected in CSF or whole blood in 4 of 7 episodes in this series. We demonstrate moderate sensitivity of strain typing in ocular syphilis using non-ocular clinical specimens.

The genomes of the yaws bacterium, Treponema pallidum subsp. pertenue, of nonhuman primate and human origin are not genomically distinct

BACKGROUND

Treponema pallidum subsp. pertenue (TPE) is the causative agent of human yaws. Yaws is currently reported in 13 endemic countries in Africa, southern Asia, and the Pacific region. During the mid-20th century, a first yaws eradication effort resulted in a global 95% drop in yaws prevalence. The lack of continued surveillance has led to the resurgence of yaws. The disease was believed to have no animal reservoirs, which supported the development of a currently ongoing second yaws eradication campaign. Concomitantly, genetic evidence started to show that TPE strains naturally infect nonhuman primates (NHPs) in sub-Saharan Africa. In our current study we tested hypothesis that NHP- and human-infecting TPE strains differ in the previously unknown parts of the genomes.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we determined complete (finished) genomes of ten TPE isolates that originated from NHPs and compared them to TPE whole-genome sequences from human yaws patients. We performed an in-depth analysis of TPE genomes to determine if any consistent genomic differences are present between TPE genomes of human and NHP origin. We were able to resolve previously undetermined TPE chromosomal regions (sequencing gaps) that prevented us from making a conclusion regarding the sequence identity of TPE genomes from NHPs and humans. The comparison among finished genome sequences revealed no consistent differences between human and NHP TPE genomes.

CONCLUSION/SIGNIFICANCE

Our data show that NHPs are infected with strains that are not only similar to the strains infecting humans but are genomically indistinguishable from them. Although interspecies transmission in NHPs is a rare event and evidence for current spillover events is missing, the existence of the yaws bacterium in NHPs is demonstrated. While the low risk of spillover supports the current yaws treatment campaign, it is of importance to continue yaws surveillance in areas where NHPs are naturally infected with TPE even if yaws is successfully eliminated in humans.

Treponema pallidum Strains Among Women and Men Who Have Sex With Women in Amsterdam, the Netherlands and Antwerp, Belgium Between 2014 and 2020

ABSTRACT

The Treponema pallidum strain distribution among men who have sex with women were similar to the strain distribution men who have sex with men. The most prevalent strains and percentage of strains belonging to the Nichols lineage are similar to previous studies in Amsterdam focusing on men who have sex with men.

High frequency of Nichols-like strains and increased levels of macrolide resistance in Treponema pallidum in clinical samples from Buenos Aires, Argentina

Globally, 94% of Treponema pallidum subsp. pallidum (TPA) clinical strains belong to the SS14-like group and 6% to the Nichols-like group, with a prevalence of macrolide resistance of 90%. Our goal was to determine whether local TPA strain distribution and macrolide resistance frequency have changed significantly since our last report, which revealed that Buenos Aires had a high frequency of Nichols-like strains (27%) and low levels of macrolide resistance (14%). Swab samples from patients with suspected syphilis were collected during 2015–2019 and loci TP0136, TP0548, TP0705 were sequenced in order to perform multilocus sequence typing. Strains were classified as Nichols-like or SS14-like. The presence of macrolide resistance-associated mutations was determined by examination of the 23S rDNA gene sequence. Of 46 typeable samples, 37% were classified as Nichols-like and 63% as SS14-like. Macrolide resistance prevalence was 45.7%. Seven allelic profiles were found, five were SS14-like and two were Nichols-like. The frequency of Nichols-like strains increased between studies (26.8% vs. 37%, p = 0.36). A dramatic increase was found in the frequency of macrolide resistant strains between studies (14.3% vs. 45.7%, p = 0.005). Our results are in agreement with international trends and underscore the need to pursue further TPA molecular typing studies in South America.

Performance of Molecular Tests in the Diagnosis of Syphilis From 2009 to 2019: A Systematic Review and Meta-Analysis

BACKGROUND

Syphilis continues to be a public health problem, and its diagnosis still has limitations. Molecular diagnosis provides an alternative for rapid and effective management. The objective is to determine the accuracy of tests in the molecular diagnosis of syphilis.

METHODS

We searched PubMed and Web of Sciences for articles related to molecular detection of syphilis from January 1, 2009, to December 31, 2019. The bivariate Reitsma model and the hierarchical receiver operating characteristic curve model were used to evaluate the diagnostic performance of molecular tests at a 95% confidence interval. A subgroup meta-analysis was performed to explore sources of heterogeneity.

RESULTS

Forty-seven articles were identified for qualitative synthesis, of which 23 met the inclusion criteria for meta-analysis. The pooled sensitivities in conventional polymerase chain reaction (PCR) and real-time PCR were 77.52 (59.50-89.01) and 68.43 (54.96-79.39), respectively. The pooled specificities were 98.00 (90.73-99.59) and 98.84 (97.55-99.46), respectively. Ulcer samples had a better performance (sensitivity of 79.88 [69.00-87.62] and specificity of 98.58 [97.25-99.27]), and the major target genes were the polymerase A gene and tpp47 gene.

CONCLUSIONS

Our work showed that conventional PCR was more widely used than real-time PCR in the diagnosis of syphilis, and ulcers were the best specimens. Sample types and target genes are factors that may influence the quality of the different tests. These results could provide evidence for further work in the direction of providing a more efficient diagnostic test.

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.

Limited Utility of Reverse Algorithm Syphilis Testing in HIV Clinic Among Men Who Have Sex With Men

BACKGROUND

The reverse algorithm for syphilis diagnosis consists of a treponemal antibody screening immunoassay followed by confirmatory nontreponemal antibody testing. It is increasingly used in the United States despite studies suggesting limited cost-effectiveness in high-prevalence groups.

METHODS

In this retrospective cross-sectional study, we included men who have sex with men tested with the reverse algorithm in an Alabama HIV clinic between March 2015 and February 2017. Trep-Sure enzyme immunoassay (EIA) was used for the initial screen, followed by reflex nontreponemal reactive rapid plasma reagin (RPR) testing of specimens with positive results. Sociodemographic and clinical data were extracted from the electronic medical record and stratified according to EIA screen positivity. Quantitative EIA antibody index values were collected to assess test performance at various thresholds.

RESULTS

Among 1693 men tested for syphilis with the reverse algorithm in HIV clinic, 808 (48%) had a positive initial EIA screen. A majority (53%) of men with subsequent RPR testing had a nonreactive RPR (EIA+/RPR-), and 19% (19/98) of these EIA+/RPR- samples tested had a negative confirmatory Treponema pallidum particle agglutination testing result. Analysis of quantitative EIA index values using a receiver operating characteristics curve suggested that a threshold >8 (rather the current threshold of antibody index 1.2) improved the performance of the test.

CONCLUSIONS

Among men who have sex with men tested in HIV clinic, the syphilis reverse algorithm was inefficient because of high rates of prior syphilis and false-positive EIA screening. Frequent syphilis screening in high-prevalence populations is an important part of the US epidemic response, and the traditional algorithm is preferred.

Ocular syphilis

Multiple studies around the world suggest that syphilis is re-emerging. Ocular syphilis - with a wide range of presentations, most of which are subtypes of uveitis - has become an increasingly common cause of ocular inflammation over the past 20 years. Its rising incidence, diagnostic complexity, and manifestations that have only recently been characterized make ocular syphilis relevant from the public health, clinical, and scientific perspectives. We review the demographics, epidemiology, clinical features, ocular imaging findings, diagnosis, and medical management of this condition.

Molecular Characterization Based on MLST and ECDC Typing Schemes and Antibiotic Resistance Analyses of Treponema pallidum subsp. pallidum in Xiamen, China

In total, 49 clinical samples were analyzed using two typing schemes, Enhanced Centers for Disease Control and Prevention (ECDC) and multilocus sequence typing (MLST), to describe the molecular characteristics of circulating Treponema pallidum isolates in Xiamen between 2016 and 2017. In addition, genetic mutations potentially related to antibiotic resistance of T. pallidum were also analyzed. Forty five samples were fully typed by ECDC, and 14 different subtypes were detected. The most common subtype was 16d/f (24.4%), followed by 14d/f (20.0%). All forty nine samples were successfully typed by MLST, while only four allelic profiles were identified, including three SS14-like profiles and one Nichols-like profile. Among them, the major allelic profile was 1.1.8 (85.7%). Interestingly, the allelic profile 1.3.1 widespread in Europe and North America was not detected in this region. Additionally, A2058G mutation in 23S rRNA was found in all detectable samples (38/38), and no mutation in 16S rRNA was observed (36/36). Four non-synonymous single-nucleotide polymorphisms in penicillin-binding protein genes were found in the 35 samples eligible for Sanger sequencing. Among them, the variant in tp0500 (P564I) can only be found in the SS14-like isolates. Homoplastic changes in tp0760 (I415F/I415M) and tp0705 (A506V/A506T) were found. Moreover, the variant tp0705 A506V and the variant tp0705 A506T separately appeared in the SS14-like isolates and Nichols-like isolates, respectively. This study showed that the genotypes of T. pallidum isolates in Xiamen between 2016 and 2017 were different from those in other geographic areas. The resistance-related variants of T. pallidum isolates identified in this study could provide awareness for clinicians in the treatment of syphilis.

2020 European guideline on the management of syphilis

The 2020 edition of the European guideline on the management of syphilis is an update of the 2014 edition. Main modifications and updates include: -The ongoing epidemics of early syphilis in Europe, particularly in men who have sex with men (MSM) -The development of dual treponemal and non-treponemal point-of-care (POC) tests -The progress in non-treponemal test (NTT) automatization -The regular episodic shortage of benzathine penicillin G (BPG) in some European countries -The exclusion of azithromycin as an alternative treatment at any stage of syphilis -The pre-exposure or immediate post-exposure prophylaxis with doxycycline in populations at high risk of acquiring syphilis.

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

Syphilis, caused by Treponema pallidum ssp. pallidum (TPA), is a persisting global health problem. Although syphilis diagnostics relies mainly on serology, serological tests have some limitations, and it is recommended that the final diagnosis be supported by additional tests. The purpose of this study was to analyze the relationship between serology and PCR in syphilis diagnostics. From the year 2004 to May 2019, a total of 941 samples were taken from 833 patients suspected of having syphilis, in Czech Republic. In all these samples, both nested PCR detection of TPA and serology testing were performed. Of the 941 samples, 126 were seronegative, 651 were seropositive, and 164 were serodiscrepant. Among seronegative samples (n = 126), 11 were PCR-positive (8.7%). Among seropositive samples (n = 651; i.e., samples positive for both non-treponemal and treponemal serology tests), 368 samples were PCR-positive (56.5%). The remaining 164 serodiscrepant samples included RPR negative and treponemal serological test-positive samples (n = 154) and a set of 10 RPR-positive samples negative in treponemal serological tests. While the first group revealed 73 PCR-positive samples (47.4%), the second revealed 5 PCR positive samples (50.0%). PCR detection rates were highest in primary syphilis, with lower rates in the secondary and undetermined syphilis stages. As shown here, the nested PCR can improve diagnostics of syphilis, especially in seronegative patients and in patients with discrepant serology.

Epidemiology, molecular strain types, and macrolide resistance of Treponema pallidum in Japan, 2017-2018

BACKGROUND

Japan has seen a substantial increase in syphilis cases since 2013 and Tokyo and Osaka prefectures accounted for about 40% of all cases in Japan. Therefore, focusing on these 2 prefectures, we assessed syphilis cases detected during 2017-2018, combining epidemiological information with molecular typing data.

METHODS

Using data from surveillance reports, we described syphilis cases by gender, age, transmission route, and stage of syphilis. Clinical specimens were collected from syphilis patients in Tokyo and Osaka prefectures. Molecular typing was performed by analyzing Treponema pallidum arp, tpr, and tp0548 genes, with partial sequencing of the 23S rRNA genes for macrolide resistance.

RESULTS

Between 2017 and 2018, the number of syphilis cases increased from 3934 to 4588 among males and 1895 to 2414 among females, with similar age and gender distributions during the period. The predominant strain type was 14d/f (71%, 73/103), found more frequently in women who have sex with men (86%, 25/29) and men who have sex with women (83%, 39/47) than in men who have sex with men (MSM) (33%, 9/27). The majority of the strains from heterosexuals (97%, 76/78) were macrolide-resistant, considerably higher than those from MSM (59%, 20/34). The molecular profiles in each sexual-transmission group remained similar during the 2 years.

CONCLUSIONS

The epidemiological and molecular features of syphilis remained similar throughout the period, with consistent differences in strain type and macrolide resistance distributions between MSM and heterosexual cases. These findings suggest a predominantly heterosexual epidemic where the dynamics of syphilis transmission remained unchanged during 2017-2018.

Increased Discrimination of Treponema pallidum Strains by Subtyping With a 4-Component System Incorporating a Mononucleotide Tandem Repeat in rpsA

A guanine mononucleotide repeat in the rpsA (tp0279) gene was evaluated for improved strain discrimination using 72 Treponema pallidum-positive specimens. The tandem repeat combined with the enhanced Centers for Disease Control and Prevention typing system resulted in increased discrimination and should be useful for molecular epidemiologic studies on syphilis especially in outbreaks and among men who have sex with men.

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.

MLST typing of Treponema pallidum subsp. pallidum in the Czech Republic during 2004-2017: Clinical isolates belonged to 25 allelic profiles and harbored 8 novel allelic variants

A recently introduced Multilocus Sequence Typing scheme for Treponema pallidum subsp. pallidum was applied to clinical samples collected from 2004 to 2017 from the two largest cities (Prague and Brno) in the Czech Republic. Altogether, a total of 675 samples were tested in this study and 281 of them were found PCR-positive for treponemal DNA and typeable. Most of the typed samples (n = 281) were swabs from primary or secondary syphilis lesions (n = 231), and only a minority were whole blood or tissue samples (n = 50). Swab samples from patients with rapid plasma regain (RPR) values of 1–1024 were more frequently PCR-positive (84.6%) compared to samples from patients with non-reactive RPR test (46.5%; p-value = 0.0001). Out of 281 typeable samples, 136 were fully-typed at all TP0136, TP0548, and TP0705 loci. Among the fully and partially typed samples, 25 different allelic profiles were identified. Altogether, eight novel allelic variants were found among fully (n = 5) and partially (n = 3) typed samples. The distribution of TPA allelic profiles identified in the Czech Republic from 2004 to 2017 revealed a dynamic character with allelic profiles disappearing and emerging over time. While the number of samples with the A2058G mutation was seen to increase (86.7% in 2016/2017), the number of samples harboring the A2059G mutation was found to have decreased over time (3.3% in 2016/2017). In addition, we found several allelic profile associations with macrolide resistance or susceptibility, the gender of patients, as well as patient residence.

A public database for the new MLST scheme for Treponema pallidum subsp. pallidum: surveillance and epidemiology of the causative agent of syphilis

Treponema pallidum subsp. pallidum is the causative agent of syphilis, a sexually transmitted disease with worldwide prevalence. Several different molecular typing schemes are currently available for this pathogen. To enable population biology studies of the syphilis agent and for epidemiological surveillance at the global scale, a harmonized typing tool needs to be introduced. Recently, we published a new multi-locus sequence typing (MLST) with the potential to significantly enhance the epidemiological data in several aspects (e.g., distinguishing genetically different clades of syphilis, subtyping inside these clades, and finally, distinguishing different subspecies of non-cultivable pathogenic treponemes). In this short report, we introduce the PubMLST database for treponemal DNA data storage and for assignments of allelic profiles and sequencing types. Moreover, we have summarized epidemiological data of all treponemal strains (n = 358) with available DNA sequences in typing loci and found several association between genetic groups and characteristics of patients. This study proposes the establishment of a single MLST of T. p. pallidum and encourages researchers and public health communities to use this PubMLST database as a universal tool for molecular typing studies of the syphilis pathogen.

Epidemiological Features of Hand, Foot and Mouth Disease Outbreaks among Chinese Preschool Children: A Meta-analysis

BACKGROUND

Hand-foot-mouth disease (HFMD) is a widespread communicable disease and has caused large epidemics in many countries. This meta-analysis aimed to analyze and evaluate the epidemiological features of HFMD outbreaks in Chinese preschools.

METHODS

Literature review was based on PubMed, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases from 2008 to 2015. The temporal, spatial and demographic parameters were summarized and analyzed.

RESULTS

Overall, 19 studies with a total of 11269 HFMD cases were selected for data synthesis and analysis. April, May, June and July were detected as the peak months of HFMD outbreaks, with the pooled rate of 21% (95% CI: 12%-34%), 23% (95% CI: 19%-27%), 20% (95% CI: 17%-24%) and 11% (95% CI: 7%-15%). Urban areas were at a higher risk of suffering from HFMD outbreaks than rural areas, with the pooled rate of 65% (95% CI: 48%-78%) and 35% (95% CI: 22%-52%) respectively. The constituent ratio of children aged 37-48 months is the highest, accounting for 46% (95% CI: 39%-53%) of the total cases during HFMD outbreaks. The pooled rate of male cases (60%) was higher than that of female cases (40%).

CONCLUSION

Month, residence, age, and gender may be early risk factors for potential HFMD outbreaks. Before the advent of peak months from Apr to Jul each year, measures should be taken to prevent the HFMD outbreaks among preschool children in China. Preschools located in urban areas should take priority over special prevention. HFMD surveillance should preferentially focus on children aged 37-48 months, especially boys in preschools.

Molecular characterization of Treponema pallidum subsp. pallidum in Switzerland and France with a new multilocus sequence typing scheme

Syphilis is an important public health problem and an increasing incidence has been noted in recent years. Characterization of strain diversity through molecular data plays a critical role in the epidemiological understanding of this re-emergence. We here propose a new high-resolution multilocus sequence typing (MLST) scheme for Treponema pallidum subsp. pallidum (TPA). We analyzed 30 complete and draft TPA genomes obtained directly from clinical samples or from rabbit propagated strains to identify suitable typing loci and tested the new scheme on 120 clinical samples collected in Switzerland and France. Our analyses yielded three loci with high discriminatory power: TP0136, TP0548, and TP0705. Together with analysis of the 23S rRNA gene mutations for macrolide resistance, we propose these loci as MLST for TPA. Among clinical samples, 23 allelic profiles as well as a high percentage (80% samples) of macrolide resistance were revealed. The new MLST has higher discriminatory power compared to previous typing schemes, enabling distinction of TPA from other treponemal bacteria, distinction between the two main TPA clades (Nichols and SS14), and differentiation of strains within these clades.

Multi-locus sequence typing of Treponema pallidum subsp. pallidum present in clinical samples from France: Infecting treponemes are genetically diverse and belong to 18 allelic profiles

Treponema pallidum subsp. pallidum, the causative agent of sexually transmitted syphilis, detected in clinical samples from France, was subjected to molecular typing using the recently developed Multilocus Sequence Typing system. The samples (n = 133) used in this study were collected from 2010-2016 from patients with diagnosed primary or secondary syphilis attending outpatient centers or hospitals in several locations in France. Altogether, 18 different allelic profiles were found among the fully typed samples (n = 112). There were five allelic variants identified for TP0136, 12 for TP0548, and eight for TP0705. Out of the identified alleles, one, seven, and three novel alleles were identified in TP0136, TP0548, and TP0705, respectively. Partial allelic profiles were obtained from 6 samples. The majority of samples (n = 110) belonged to the SS14-like cluster of TPA isolates while 7 clustered with Nichols-like isolates. Patients infected with Nichols-like samples were more often older (p = 0.041) and more often diagnosed with secondary syphilis (p = 0.033) compared to patients infected with SS14-like samples. In addition, macrolide resistance caused by the A2058G mutation was found to be associated with allelic profile 1.3.1 or with strains belonging to the 1.3.1 lineage (p<0.001). The genetic diversity among TPA strains infecting the European population was surprisingly high, which suggests that additional studies are needed to reveal the full genetic diversity of TPA pathogens infecting humans.

Sequence Variation of Rare Outer Membrane Protein β-Barrel Domains in Clinical Strains Provides Insights into the Evolution of Treponema pallidum subsp. pallidum, the Syphilis Spirochete

In recent years, considerable progress has been made in topologically and functionally characterizing integral outer membrane proteins (OMPs) of Treponema pallidum subspecies pallidum, the syphilis spirochete, and identifying its surface-exposed β-barrel domains. Extracellular loops in OMPs of Gram-negative bacteria are known to be highly variable. We examined the sequence diversity of β-barrel-encoding regions of tprC, tprD, and bamA in 31 specimens from Cali, Colombia; San Francisco, California; and the Czech Republic and compared them to allelic variants in the 41 reference genomes in the NCBI database. To establish a phylogenetic framework, we used T. pallidum 0548 (tp0548) genotyping and tp0558 sequences to assign strains to the Nichols or SS14 clades. We found that (i) β-barrels in clinical strains could be grouped according to allelic variants in T. pallidum subsp. pallidum reference genomes; (ii) for all three OMP loci, clinical strains within the Nichols or SS14 clades often harbored β-barrel variants that differed from the Nichols and SS14 reference strains; and (iii) OMP variable regions often reside in predicted extracellular loops containing B-cell epitopes. On the basis of structural models, nonconservative amino acid substitutions in predicted transmembrane β-strands of T. pallidum repeat C (TprC) and TprD2 could give rise to functional differences in their porin channels. OMP profiles of some clinical strains were mosaics of different reference strains and did not correlate with results from enhanced molecular typing. Our observations suggest that human host selection pressures drive T. pallidum subsp. pallidum OMP diversity and that genetic exchange contributes to the evolutionary biology of T. pallidum subsp. pallidum They also set the stage for topology-based analysis of antibody responses to OMPs and help frame strategies for syphilis vaccine development.IMPORTANCE Despite recent progress characterizing outer membrane proteins (OMPs) of Treponema pallidum, little is known about how their surface-exposed, β-barrel-forming domains vary among strains circulating within high-risk populations. In this study, sequences for the β-barrel-encoding regions of three OMP loci, tprC, tprD, and bamA, in T. pallidum subsp. pallidum isolates from a large number of patient specimens from geographically disparate sites were examined. Structural models predict that sequence variation within β-barrel domains occurs predominantly within predicted extracellular loops. Amino acid substitutions in predicted transmembrane strands that could potentially affect porin channel function were also noted. Our findings suggest that selection pressures exerted within human populations drive T. pallidum subsp. pallidum OMP diversity and that recombination at OMP loci contributes to the evolutionary biology of syphilis spirochetes. These results also set the stage for topology-based analysis of antibody responses that promote clearance of T. pallidum subsp. pallidum and frame strategies for vaccine development based upon conserved OMP extracellular loops.

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.

Molecular Typing of Treponema pallidum in Ocular Syphilis

BACKGROUND

Syphilis can have many clinical manifestations, including eye involvement, or "ocular syphilis." In 2015, an increase in reported cases of ocular syphilis and potential case clusters raised concern for an oculotropic strain of Treponema pallidum, the infectious agent of syphilis. Molecular typing was used to examine strains found in cases of ocular syphilis in the United States.

METHODS

In 2015, after a clinical advisory issued by the Centers for Disease Control and Prevention, pretreatment clinical specimens from US patients with ocular syphilis were sent to a research laboratory for molecular analysis of T. pallidum DNA. Molecular typing was conducted on these specimens, and results were compared with samples collected from Seattle patients diagnosed with syphilis, but without ocular symptoms.

RESULTS

Samples were typed from 18 patients with ocular syphilis and from 45 patients with syphilis, but without ocular symptoms. Clinical data were available for 14 ocular syphilis patients: most were men, human immunodeficiency virus-infected, and had early syphilis. At least 5 distinct strain types of Treponema pallidum were identified in these patients, and 9 types were identified in the Seattle nonocular patients. 14d/g was the most common type in both groups. An unusual strain type was detected in a small cluster of ocular syphilis patients in Seattle.

CONCLUSIONS

Ocular syphilis is a serious sequela of syphilis. In this preliminary study, clear evidence of a predominant oculotropic strain causing ocular syphilis was not detected. Identification of cases and prompt treatment is critical in the management of ocular syphilis.

Whole genome sequence of the Treponema pallidum subsp. pallidum strain Amoy: An Asian isolate highly similar to SS14

Treponema pallidum ssp. pallidum (T. pallidum), the causative agent of the sexually transmitted disease syphilis, is an uncultivatable human pathogen. The geographical differences in T. pallidum genomes leading to differences in pathogenicity are not yet understood. Presently, twelve T. pallidum genomes are available to the public, all of which are American in origin and often co-infect patients with human immunodeficiency virus (HIV). In this study, we examined the T. pallidum subsp. pallidum strain Amoy, a syphilis pathogen found in Xiamen, China. We sequenced its genome using Illumina next-generation sequencing technology and obtained a nearly (98.83%) complete genome of approximately 1.12 Mbps. The new genome shows good synteny with its five T. pallidum sibling strains (Nichols, SS14, Mexico A, DAL-1, and Chicago), among which SS14 is the strain closest to the Amoy strain. Compared with strain SS14, the Amoy strain possesses four uncharacterized strain-specific genes and is likely missing six genes, including a gene encoding the TPR domain protein, which may partially account for the comparatively low virulence and toxicity of the Amoy strain in animal infection. Notably, we did not detect the 23S rRNA A2058G/A2059G mutation in the Amoy strain, which likely explains the sensitivity of Amoy strain to macrolides. The results of this study will lead to a better understanding of the pathogenesis of syphilis and the geographical distribution of T. pallidum genotypes.

Molecular epidemiological survey of Treponema pallidum in pregnant women in the Zhabei District of Shanghai

PURPOSE

To evaluate the epidemiological characteristics of syphilis, such as incidence, vertical transmission and genotypes, in pregnant women in the Zhabei District of Shanghai. In addition, the changes in genotypes and the efficiency of genotyping were evaluated.

METHODOLOGY

We screened 3022 pregnant women for syphilis in the Shanghai Zhabei Central Hospital. Whole blood, plasma, earlobe blood and specimens from genital ulcers or skin/mucosal lesions were collected from syphilis-positive patients. Samples were genotyped by analysing a combination of three genes: tpr, arp and tp0548 (the tpr/arp/tp0548 genotype). Clinical data were further collected to evaluate disease incidence, maternal-neonatal transmission and social factors.

RESULTS

Out of 3022 pregnant women screened for syphilis, 41 were syphilis-positive. Of these, 43.9 % showed vertical transmission (18/41). The prevalence of syphilis in pregnant women was 1.32 %, higher than that in other districts in Shanghai in 2014. Genotyping was performed in 10/11 (90.9 %) samples of syphilis lesions, 8/41 (19.5 %) blood samples, 12/41 (29.3 %) plasma samples, and 20/39 (48.7 %) earlobe blood samples. The predominant genotype was 14d/f, followed by 15d/f, 13a/f, 13d/f and 9o/c. Genotype 13a/f was reported for the first time in the Shanghai area since 2010.

CONCLUSION

The prevalence of syphilis in pregnant women in the Zhabei District was higher than that in other areas in Shanghai and the genotype is variable.

Re-evaluating the sensitivity of the rabbit infectivity test for Treponema pallidum in modern era

BACKGROUND

The rabbit infectivity test (RIT) was previously described as a highly-sensitive method for clinically detecting Treponema pallidum. But our primary study indicated this result may have changed in current antibiotics era.

METHODS

By inoculating rabbits testis with cerebrospinal fluid (CSF) (n=63) and exudate from hard chancre lesions (n=13), we re-evaluated the sensitivity of RIT in modern era. All isolated T. pallidum strains from the RIT were performed for the strain type based on "CDC subtype/tp0548" method. Chi-square and Fisher's exact tests were used to determine the statistical significance of differences across data sets.

RESULTS

Result indicated that 2 of 63 CSF (2/63, 3.17%) and 5 of 13 lesion exudate samples (5/13, 38.47%) were positive in the RIT, with a much longer time to detection for CSF samples. Only 1 of 28 samples from patients who admitted treatment with antibiotics prior to clinical exam was positive in the RIT; while 6 of 48 patients, who admitted no recent exposure to antibiotics or was unclear about the medical history, were positive in RIT. DNA sequence analysis revealed 6 strains of 14d/f subtype and one strain of 14a/f subtype.

CONCLUSIONS

In conclusions, RIT is no longer a highly sensitive method for detecting T. pallidum in clinical samples as before, and is not inadequately considered to be a reference method for measuring the sensitivity of other new methods, such as the PCR. These data represent the first reexamination of the sensitivity of RIT in the post-antibiotic era with a large clinical sample.

Syphilis epidemiology in 1994-2013, molecular epidemiological strain typing and determination of macrolide resistance in Treponema pallidum in 2013-2014 in Tuva Republic, Russia

The incidence of syphilis in the Tuva Republic (geographical centre of Asia), Russia has been exceedingly high historically. No detailed examinations and no molecular investigations of Treponema pallidum strains transmitted in the Tuva Republic, or in general, in Russia, were published internationally. We examined the syphilis epidemiology in 1994-2013, and the molecular epidemiology and macrolide resistance in T. pallidum strains in 2013-2014 in the Tuva Republic. Among 95 mainly primary or secondary syphilis patients, the arp, tpr, tp0548 and 23S rRNA genes in 85 polA gene-positive genital ulcer specimens were characterized. The syphilis incidence in Tuva Republic peaked in 1998 (1562), however declined to 177 in 2013. Among the 70 (82%) completely genotyped specimens, six molecular strain types were found. Strain type 14d/f accounted for 91%, but also 14c/f, 14d/g, 14b/f, 14i/f, 9d/f, and 4d/f were identified. Two (2.4%) specimens contained the 23S rRNA A2058G macrolide resistance mutation. This is the first internationally published typing study regarding T. pallidum in Russia, performed in the Tuva Republic with the highest syphilis incidence in Russia. The two molecular strain types 4d/f and 9d/f have previously been described only in Eastern and Northern China and for the first time, macrolide-resistant syphilis was described in Russia.

Syphilis testing, typing, and treatment follow-up: a new era for an old disease

PURPOSE OF REVIEW

The past 15 years have seen a dramatic increase in syphilis diagnoses in several regions including China, North America, Western Europe and Australia. Worldwide, the disease remains prevalent, contributing to substantial adult morbidity and neonatal mortality. Testing and treatment strategies are largely informed by data from the early antibiotic era, but increasing use of molecular diagnostics and new screening strategies could improve the management of syphilis substantially.

RECENT FINDINGS

The review explores new testing strategies for syphilis, including the importance of screening test selection and advances in point-of-care diagnostics. It then examines molecular studies of Treponema pallidum, covering typing; macrolide resistance; association between genotype and phenotype and the use of PCR in testing and monitoring strategies.

SUMMARY

Clinicians should be aware of testing strategies employed by their laboratories to ensure optimal sensitivity and specificity. Locally available T. pallidum PCR assays may improve the diagnosis of early disease and inform antibiotic choice. Robust serologic follow-up is still required, but predictors of potential treatment failure, including PCR-measured bacterial load, have been identified. Re-treatment should be considered for patients in the serofast state. The publication of T. pallidum genomes would allow further and more detailed study of strains and disease pathogenesis.

Unexpectedly high prevalence of Treponema pallidum infection in the oral cavity of human immunodeficiency virus-infected patients with early syphilis who had engaged in unprotected sex practices

Between 2010 and 2014, we obtained swab specimens to detect Treponema pallidum, with PCR assays, from the oral cavities of 240 patients with 267 episodes of syphilis who reported engaging in unprotected sex practices. The detected treponemal DNA was subjected to genotyping. All of the syphilis cases occurred in men who have sex with men (MSM), and 242 (90.6%) occurred in human immunodeficiency virus-infected patients. The stages of syphilis included 38 cases (14.2%) of primary syphilis of the genital region, 76 (28.5%) of secondary syphilis, 21 (7.9%) of primary and secondary syphilis, 125 (46.8%) of early latent syphilis, and seven (2.6%) others. Concurrent oral ulcers were identified in 22 cases (8.2%). Treponemal DNA was identified from the swabs of 113 patients (42.2%), including 15 (68.2%) with oral ulcers. The most common genotype of T. pallidum was 14f/f. The presence of oral ulcers was associated with identification of T. pallidum in the swab specimens (15/22 (68.2%) vs. 98/245 (40.0%)) (p = 0.01). In multivariate analysis, secondary syphilis (adjusted OR 6.79; 95% CI 1.97-23.28) and rapid plasma reagin (RPR) titres of ≥1: 32 (adjusted OR 2.23; 95% CI 1.02-4.89) were independently associated with the presence of treponemal DNA in patients without oral ulcers. We conclude that detection of treponemal DNA in the oral cavity with PCR assays is not uncommon in MSM, most of whom reported having unprotected oral sex. Although the presence of oral ulcers is significantly associated with detection of treponemal DNA, treponemal DNA is more likely to be identified in patients without oral ulcers who present with secondary syphilis and RPR titres of ≥1: 32.

Current standards for diagnosis of syphilis: comparing the russian and foreign guidelines (part I)

Despite the abundance of existing laboratory methods the diagnosis of syphilis still faces many challenges. Though direct detection of T. pallidum plays an important role in early manifest forms of the disease, serological tests remain the mainstay of diagnosis. Traditional syphilis screening algorithm based on nontreponemal tests with subsequent confirmation using treponemal tests is a standard worldwide. Recently, the ability to automate the treponemal tests promotes the increasingly widespread implementation of reverse algorithm when these tests are used for syphilis screening. None of the current serological algorithms are able to reliably differentiate between active and previously treated syphilis, which causes uncertainty in the management of patients. There is no «gold standard» for the diagnosis of neurosyphilis, ocular, auricular and visceral syphilis. The interpretation of serological tests in children born to seropositive mothers is also complicated. Diagnosis of congenital syphilis in newborns and, consequently, the prescription of antibiotic therapy often depends on assessment of the adequacy of maternal treatment during pregnancy, which leads to subjective decisions. This article provides a comparative analysis of the «Federal guidelines for the management of patients with syphilis» and their foreign analogues, discusses significant peculiarities of these guidelines and reviews current concerns and controversies in syphilis diagnosis.

The molecular epidemiology of Treponema pallidum subspecies pallidum

Pathogens adapt and evolve in response to pressures exerted by host environments, leading to generation of genetically diverse variants. Treponema pallidum subspecies pallidum displays a substantial amount of interstrain diversity. These variants have been identified in various parts of the world, indicating transmission linkage between geographical regions. Genotyping is based on molecular characterisation of various loci in the syphilis treponeme genome, but still require further development and continued research, as new bacterial types are continually being detected. The goal for studying the molecular epidemiology of Treponema pallidum variants is the global monitoring of the transmission of genetically distinct organisms with different drug sensitivities and, potentially, different virulence proprieties.

Comparison of CDC and sequence-based molecular typing of syphilis treponemes: tpr and arp loci are variable in multiple samples from the same patient

Background

Molecular typing of syphilis-causing strains provides important epidemiologic data. We tested whether identified molecular subtypes were identical in PCR-positive parallel samples taken from the same patient at a same time. We also tested whether subtype prevalence differs in skin and blood samples.

Results

Eighteen syphilis positive patients (showing both positive serology and PCR), with two PCR-typeable parallel samples taken at the same time, were tested with both CDC (Centers for Disease Control and Prevention) and sequence-based typing. Samples taken from 9 of 18 patients were completely typed for TP0136, TP0548, 23S rDNA, arp, and tpr loci. The CDC typing revealed 11 distinct genotypes while the sequence-based typing identified 6 genotypes. When results from molecular typing of TP0136, TP0548, and 23S rDNA were analyzed in samples taken from the same patient, no discrepancies in the identified genotypes were found; however, there were discrepancies in 11 of 18 patients (61.1%) samples relative to the arp and tpr loci. In addition to the above described typing, 127 PCR-positive swabs and whole blood samples were tested for individual genotype frequencies. The repetition number for the arp gene was lower in whole blood (WB) samples compared to swab samples. Similarly, the most common tpr RFLP type “d” was found to have lower occurrence rates in WB samples while type “e” had an increased occurrence in these samples.

Conclusions

Differences in the CDC subtypes identified in parallel samples indicated genetic instability of the arp and tpr loci and suggested limited applicability of the CDC typing system in epidemiological studies. Differences in treponemal genotypes detected in whole blood and swab samples suggested important differences between both compartments and/or differences in adherence of treponeme variants to human cells.

Factors associated with serological cure and the serofast state of HIV-negative patients with primary, secondary, latent, and tertiary syphilis

BACKGROUND

Some syphilis patients remain in a serologically active state after the recommended therapy. We currently know too little about the characteristics of this serological response.

METHODS

We conducted a cohort study using the clinical database from Zhongshan Hospital, Medical College of Xiamen. In total, 1,327 HIV-negative patients with primary, secondary, latent, and tertiary syphilis were enrolled. Bivariate and multivariate analyses were utilised to identify factors associated with a serological cure and serofast state in syphilis patients one year after therapy. Chi-square tests were used to determine the differences in the serological cure rate across different therapy time points.

RESULTS

One year after the recommended therapy, 870 patients achieved a serological cure, and 457 patients (34.4%) remained in the serofast state. The serological cure rate increased only within the first 6 months. The bivariate analysis indicated that male or younger patients had a higher likelihood of a serological cure than female or older patients. Having a baseline titre ≤ 1∶2 or ≥ 1∶64 was associated with an increased likelihood of a serological cure. The serological cure rate decreased for the different disease stages in the order of primary, secondary, latent, and tertiary syphilis. A distinction should be drawn between early and late syphilis. The multivariate analysis indicated that a serological cure was significantly associated with the disease phase, gender, age, and baseline rapid plasma reagin (RPR) titre.

CONCLUSIONS

The serofast state is common in clinical work. After one year of the recommended therapy, quite a few syphilis patients remained RPR positive. The primary endpoint of the study indicated that disease phase, gender, age and baseline RPR titre were crucial factors associated with a serological cure.

First experience of molecular typing and determining the antibiotic resistance of syphilis pathogen Treponema pallidum in the Russian Federation

The authors present the results of molecular typing and determining the antibiotic resistance of 190 T. pallidum strains sampled from primary and secondary syphilitic patients in the russian Federation in 2011—2012. molecular typing of T. pallidum strains was based on two variable gens: arp, tpr, and was supplemented with an analysis of gene tp0548 reading frame. Antibiotic resistance of syphilis strains was determined by means of sequencing the gene encoding 23S rRNA T. pallidum in such loci as A2058G and A2059G/C (resistance to macrolides), gene encoding 16S rRNA T. pallidum in locus G1058C, and determinant tetB (resistance to tetracyclines) as well as full-scale sequencing the genes encoding target proteins of β-lactams Tp47 and Tromp. As a result of molecular typing in the territory of the Russian Federation, ten subtypes of T. pallidum were revealed. Type 14 (98.4%) predominates; the share of subtype 14d/f is 91.03%; the share of subtypes 14d/Tand 14b/f, Type 14, was 2.10 and 3.16%, respectively; the share of all other subtypes (11d/f, 13d/f, 14a/a, 14a/f, 14d/g, 14d/c, 20d/f) was 0.53%. molecular markers of T. pallidum antibiotic resistance were revealed among the strains coming from the Central, Siberian and Volga federal regions of Russia: macrolides - three strains sampled in 2011; tetracyclines - two strains sampled in 2011 and one strain sampled in 2012.

Whole-genome sequencing of bacterial sexually transmitted infections: implications for clinicians

PURPOSE OF REVIEW

Increasingly, genomics is being used to answer detailed clinical questions. Although genome analysis of bacterial sexually transmitted infections (STIs) lags far behind that of many other bacterial pathogens, genomics can reveal previously inaccessible aspects of pathogen biology.

RECENT FINDINGS

Comparative genomic studies on the most common bacterial STI, chlamydia, have revolutionized our understanding of this intracellular bacterium, demonstrating that it undergoes extensive recombination and that the traditional typing schemes can be misleading. Genome projects can also help us to understand the recently observed phenomenon of 'diagnostic escape' seen in both Chlamydia trachomatis and Neisseria gonorrhoeae.

SUMMARY

The routine use of genomics in clinical settings is becoming a reality. For STIs, a primary requirement is an understanding of the diversity of circulating strains and how they change over time. This can help to inform future studies and allow us to address real clinical issues such as outbreak identification, global spread of successful clones and antimicrobial resistance monitoring.

The laboratory diagnostics of syphilis: yesterday, today, tomorrow

The article covers issues related to the development of laboratory methods used for the diagnostic of syphilitic infection in the historical aspect as well as for the nearest and remote future. Priorities of the application of several diagnostic methods have been highlighted depending on the stage and form of syphilis, on the performed specific treatment and the contingent of examined patients. The authors give recommendations for its use reflected in modern Russian and foreign manuals and standards of syphilis diagnostics. Laboratory methods such as immunochemiluminescence assay, хМАР-technology and aspects of their clinical application are specially highlighted. The authors provide data on applied methods of molecular typing of Т. pallidum and detection of genetic determinants of the resistance of the syphilis pathogen to antimicrobial substances.

Neonate human remains: a window of opportunity to the molecular study of ancient syphilis

Ancient DNA (aDNA) analysis can be a useful tool in bacterial disease diagnosis in human remains. However, while the recovery of Mycobacterium spp. has been widely successful, several authors report unsuccessful results regarding ancient treponemal DNA, casting doubts on the usefulness of this technique for the diagnosis of ancient syphilis. Here, we present results from an analysis of four newborn specimens recovered from the crypt of "La Ermita de la Soledad" (XVI-XVII centuries), located in the province of Huelva in the southwest of Spain. We extracted and analyzed aDNA in three independent laboratories, following specific procedures generally practiced in the aDNA field, including cloning of the amplified DNA fragments and sequencing of several clones. This is the most ancient case, reported to date, from which detection of DNA from T. pallidum subspecies pallidum has been successful in more than one individual, and we put forward a hypothesis to explain this result, taking into account the course of the disease in neonate individuals.