Molecular subtyping of Treponema pallidum in an Arizona County with increasing syphilis morbidity: use of specimens from ulcers and blood

High-throughput nanopore sequencing of Treponema pallidum tandem repeat genes arp and tp0470 reveals clade-specific patterns and recapitulates global whole genome phylogeny

Sequencing of most Treponema pallidum genomes excludes repeat regions in tp0470 and the tp0433 gene, encoding the acidic repeat protein (arp). As a first step to understanding the evolution and function of these genes and the proteins they encode, we developed a protocol to nanopore sequence tp0470 and arp genes from 212 clinical samples collected from ten countries on six continents. Both tp0470 and arp repeat structures recapitulate the whole genome phylogeny, with subclade-specific patterns emerging. The number of tp0470 repeats is on average appears to be higher in Nichols-like clade strains than in SS14-like clade strains. Consistent with previous studies, we found that 14-repeat arp sequences predominate across both major clades, but the combination and order of repeat type varies among subclades, with many arp sequence variants limited to a single subclade. Although strains that were closely related by whole genome sequencing frequently had the same arp repeat length, this was not always the case. Structural modeling of TP0470 suggested that the eight residue repeats form an extended α-helix, predicted to be periplasmic. Modeling of the ARP revealed a C-terminal sporulation-related repeat (SPOR) domain, predicted to bind denuded peptidoglycan, with repeat regions possibly incorporated into a highly charged β-sheet. Outside of the repeats, all TP0470 and ARP amino acid sequences were identical. Together, our data, along with functional considerations, suggests that both TP0470 and ARP proteins may be involved in T. pallidum cell envelope remodeling and homeostasis, with their highly plastic repeat regions playing as-yet-undetermined roles.

Development of multiplex HRM-based loop-mediated isothermal amplification method for specific and sensitive detection of Treponema pallidum

Syphilis is a sexually transmitted disease caused by the spirochaete bacterium Treponema pallidum. This study has developed a multiplex High-Resolution Melt-curve Loop-mediated isothermal amplification (multiplex HRM-LAMP) assay targeting the marker genes polA and tprL to detect T. pallidum. The multiplex HRM-LAMP assay conditions were optimized at 65 °C for 45 min. Real-time melt-curve analysis of multiplex HRM-LAMP shows two melt-curve peaks corresponding to polA and tprL with a Tm value of 80 ± 0.5 °C and 87 ± 0.5 °C, respectively. The detection limit of multiplex HRM-LAMP was found to be 6.4 × 10^-4 ng/μL (3.79 copies/μL) of T. pallidum. The specificity was evaluated using seven different bacterial species, and the developed method was 100% specific in detecting T. pallidum. A total of 64 blood samples of T. pallidum suspected cases were used to validate the assay method. The clinical validation showed that the assay was 96.43% sensitive and 100% specific in detecting syphilis. Thus, the developed method was more rapid and sensitive than other available methods and provides a multigene-based diagnostic approach to detect T. pallidum.

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.

Multilocus sequence typing of Treponema pallidum subsp. pallidum in Barcelona

Aim: To implement the multilocus sequence typing (MLST) methodology in syphilis samples previously characterized by enhanced CDC typing (ECDCT) and macrolide resistance. Materials & methods: MLST was performed on genital ulcer and blood samples by analyzing a region of the tp0136, tp0548 and tp0705 loci using Sanger sequencing. Results: Up to 59/85 (69.4%) of genital ulcer and 4/39 (10.3%) of whole blood samples were fully typed. The most frequent profiles were 1.3.1 (56%) and 1.1.1 (11%). All the 1.3.1 samples typed carried the A2058G mutation, responsible for macrolide resistance. MLST and ECDCT showed similar overall typing yields. Conclusion: Several allelic profiles of T. pallidum subsp. pallidum were identified and classified into two major genetic clades in Barcelona. Our results were similar to that described in Europe.

A Novel Nested Real-time Polymerase Chain Reaction for Treponema pallidum DNA in Syphilis Biospecimens

BACKGROUND

Early diagnosis of Treponema pallidum infection is helpful for disease management, and conventional PCR is suitable for lesion swabs of patients with probable early syphilis. We thus tested nested and real-time PCR (NR-PCR) in various biosamples from syphilitic patients.

METHODS

Samples were collected from syphilis patients before treatment. Specific primer sequences targeting the T. pallidum gene polA were designed for NR-PCR.

RESULTS

Across syphilis types, most samples assayed with NR-PCR returned a positive result, including earlobe blood (92.0%), cerebrospinal fluid (CSF) (90.2%), lesion swabs (74.3%), serum (66.9%), and whole blood (64.2%). No significant differences were observed in positive samples for whole blood, serum, and lesion swabs between primary and secondary syphilis (P > 0.05 for all comparisons). However, more whole-blood samples from patients with secondary syphilis were positive for NR-PCR than whole blood samples from patients with tertiary and latent syphilis (P < 0.05 for all comparisons). For neurosyphilis patients, significantly more earlobe blood samples tested positive than did whole-blood samples (P < 0.05), but there was no difference in positive results for earlobe blood and whole blood in latent syphilis. Significantly more serum samples tested positive in latent syphilis patients with rapid plasma regain (RPR) titers of 1:8 or greater, compared to those with RPR of 1:4 or less.

CONCLUSIONS

Nested and real-time PCR can be used to identify T. pallidum DNA in biosamples from syphilitic patients, especially earlobe blood.

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.

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 Subtyping and Surveillance of Resistance Genes In Treponema pallidum DNA From Patients With Secondary and Latent Syphilis in Hunan, China

BACKGROUND

Over the past decade, the incidence of syphilis and widespread macrolide resistance in its etiological agent, Treponema pallidum subsp. pallidum, have become a major health concern across countries, including China. Regional trends in subtypes and antibiotic resistance can be monitored effectively by molecular surveillance programs. In this study, whole blood samples were used to assess circulating T. pallidum strains collected from various regions of Hunan, China, between 2013 and 2015.

METHODS

Traditional polymerase chain reaction, targeting polA, tpp47, bmp, and tp0319 genes, was used as preliminary screening assay. About 455 polymerase chain reaction-positive specimens were obtained from 2253 whole blood samples of patients with secondary or latent syphilis. Molecular subtyping was performed using a Centers for Disease Control and Prevention-based typing method combined with an analysis of the variable region of tp0548 gene. Resistance to macrolides was analyzed by examining point mutations in 23S rRNA, and the presence of the G1058C point mutation within 16S rRNA associated with decreased susceptibility to doxycycline was assessed.

RESULTS

Circulating T. pallidum strains were resolved into 32 subtypes, among which subtype 14d/f was predominant. A2059G mutation in 23S rRNA, and the G1058C mutation in 16S rRNA was absent, but the prevalence of A2058G mutation in 23S rRNA was 97.5%.

CONCLUSIONS

We found that it is possible to use whole blood to evaluate molecular subtypes and monitor antibiotic resistance in circulating T. pallidum strains, especially when chancres are absent. High frequency of macrolide-resistant T. pallidum indicates that macrolide antibiotics, such as azithromycin, should be avoided as a treatment option for syphilis in Hunan, China.

Comparison of Diagnostic Accuracy of PCR Targeting the 47-Kilodalton Protein Membrane Gene of Treponema pallidum and PCR Targeting the DNA Polymerase I Gene: Systematic Review and Meta-analysis

Treponema pallidum PCR (Tp-PCR) testing now is recommended as a valid tool for the diagnosis of primary or secondary syphilis. The objectives were to systematically review and determine the optimal specific target gene to be used for Tp-PCR. Comparisons of the performance of the two main targets are tpp47 and polA genes were done using meta-analysis. Three electronic bibliographic databases, representing abstract books from five conferences specialized in infectious diseases from January 1990 to March 2015, were searched. Search keywords included ("syphilis" OR "Treponema pallidum" OR "neurosyphilis") AND ("PCR" OR "PCR" OR "molecular amplification"). We included diagnostic studies assessing the performance of Tp-PCR targeting tpp47 (tpp47-Tp-PCR) or the polA gene (polA-Tp-PCR) in ulcers from early syphilis. All studies were assessed against quality criteria using the QUADAS-2 tool. Of 37 studies identified, 62.2% were judged at low risk of bias or applicability. Most used the U.S. Centers for Disease Control and Prevention (CDC) case definitions for primary or secondary (early) syphilis (89.2%; n = 33); 15 (40.5%) used darkfield microscopy (DFM). We did not find differences in sensitivity and specificity between the two Tp-PCR methods in the subgroup of studies using adequate reference tests. Among studies using DFM as the reference test, sensitivities were 79.8% (95% confidence intervals [CI], 72.7 to 85.4%) and 71.4% (46.0 to 88.0%) for tpp47-Tp-PCR and polA-Tp-PCR (P = 0.217), respectively; respective specificities were 95.3% (93.5 to 96.6%) and 93.7% (91.8 to 95.2%) (P = 0.304). Our findings suggest that the two Tp-PCR methods have similar accuracy and could be used interchangeably.

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.

Canadian Public Health Laboratory Network laboratory guidelines for the use of direct tests to detect syphilis in Canada

Treponema pallidum subsp. pallidum and/or its nucleic acid can be detected by various methods such as microscopy, rabbit infectivity test or polymerase chain reaction (PCR) tests. The rabbit infectivity test for T. pallidum, although very sensitive, has been discontinued from most laboratories due to ethical issues related to the need for animal inoculation with live T. pallidum, the technically demanding procedure and long turnaround time for results, thus making it impractical for routine diagnostic use. Dark-field and phase-contrast microscopy are still useful at clinic- or hospital-based laboratories for near-bedside detection of T. pallidum in genital, skin or mucous lesions although their availability is decreasing. The lack of reliable and specific anti-T. pallidum antibodies and its inferior sensitivity to PCR may explain why the direct fluorescent antibody test for T. pallidum is not widely available for clinical use. Immunohistochemical staining for T. pallidum also depends on the availability of specific antibodies, and the method is only applicable for histopathological examination of biopsy and autopsy specimens necessitating an invasive specimen collection approach. With recent advances in molecular diagnostics, PCR is considered to be the most reliable, versatile and practical for laboratories to implement. In addition to being an objective and sensitive test for direct detection of Treponema pallidum subsp. pallidum DNA in skin and mucous membrane lesions, the resulting PCR amplicons from selected gene targets can be further characterized for antimicrobial (macrolide) susceptibility testing, strain typing and identification of T. pallidum subspecies.

Molecular typing of Treponema pallidum causing early syphilis in China: a cross-sectional study

BACKGROUND

There have been limited data on molecular epidemiology of syphilis in China. This study aimed to analyze strain type distribution of Treponema pallidum causing early syphilis across geographic areas in China using an enhanced method.

METHODS

Genital samples were collected from patients in East, South, and North China. Positive DNA of T. pallidum was analyzed by arp, tpr, and tp0548 genes.

RESULTS

Sufficient DNA for full molecular typing existed in 197 of 324 samples, and 27 strain types were identified. A range of 3 to 20 repeats (except 4, 11, and 19 repeats) and 25 repeats were found for the 60-bp tandem repeats of the arp gene. This was the first time the 9 and 25 repeats were detected. For the RFLP analysis of the tpr genes, patterns a, d, h, j, and l were identified. This was the first time the h, j, and l patterns were observed in China. For the sequence analysis of the tp0548 gene, sequences c, e, and f were identified. Strain type distribution was significantly different across geographic areas (χ² = 20.6, P = 0.006). Overall, 14d/f was most predominant (39% of fully typed samples, 95% CI = 32%-46%); 13d/f, 15d/f, and 16d/f were next most common (each 13% of fully typed samples, 95% CI = 9%-18%).

CONCLUSIONS

There is substantial genetic diversity of T. pallidum in China. The broad and ununiform distribution of strain types may reflect differences in regional sexual network patterns. Predominance of few strain types may indicate a linked transmission.

Molecular subtyping of Treponema pallidum in Paris, France

Two major Treponema pallidum subtypes, 14 d/g and 14 d/f, were identified in a population of 119 patients with syphilis in Paris, France, characterized by a high proportion of men who have sex with men. A new subtype named 11 q/j was characterized, and a reinfection case was determined in 1 patient having consecuitve syphilis infection at 19-month interval.

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.

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.

Molecular typing of Treponema pallidum: a 5-year surveillance in Shanghai, China

Previously, a small study showed that 14f was the predominant subtype of Treponema pallidum in Shanghai, China. The result was quite different from the genotype distribution in other areas of China. This study aimed to identify the strain types of Treponema pallidum in samples collected over a 5-year period in Shanghai. From 2007 to 2011, genital swabs were collected from patients with syphilis from the Shanghai Skin Disease Hospital. Positive specimens were typed by the enhanced typing method by adding a tp0548 gene to the existing arp and tpr genotype system. In total, 304 of the 372 enrolled patients yielded fully typeable DNA. Ten arp types (4, 6, 8, 9, 11, 12, 13, 14, 15, and 19), 3 tpr types (a, d, and o), and 5 tp0548 types (a, c, f, g, and i) were identified. In total, 12 subtypes were identified with a combination of the arp and tpr genes. Subtype 14d was found in 270 samples (88.8%). When the combination included the tp0548 gene, the 12 CDC subtypes identified were divided into 14 strain types. The predominant type was 14d/f (88.8%), followed by 15d/f (3.6%), 13d/f (1.3%), and 19d/c (1.3%). Two of the 44 14d/f-infected patients and both of the 19d/c-infected patients who underwent a lumbar puncture were diagnosed with neurosyphilis. This study showed that the predominant type in Shanghai was 14d/f. While this is in keeping with data from other areas in China, it is different from an earlier report showing that 14f is the most common genotype in Shanghai. Further studies are needed to better understand the association between strain types and neurosyphilis.

Evaluation of macrolide resistance and enhanced molecular typing of Treponema pallidum in patients with syphilis in Taiwan: a prospective multicenter study

Studies of macrolide resistance mutations and molecular typing using the newly proposed enhanced typing system for Treponema pallidum isolates obtained from HIV-infected patients in the Asia-Pacific region are scarce. Between September 2009 and December 2011, we conducted a survey to detect T. pallidum using a PCR assay using clinical specimens from patients with syphilis at six major designated hospitals for HIV care in Taiwan. The T. pallidum strains were genotyped by following the enhanced molecular typing methodology, which analyzed the number of 60-bp repeats in the acidic repeat protein (arp) gene, T. pallidum repeat (tpr) polymorphism, and the sequence of base pairs 131 to 215 in the tp0548 open reading frame of T. pallidum. Detection of A2058G and A2059G point mutations in the T. pallidum 23S rRNA was performed with the use of restriction fragment length polymorphism (RFLP). During the 2-year study period, 211 clinical specimens were obtained from 136 patients with syphilis. T. pallidum DNA was isolated from 105 (49.8%) of the specimens, with swab specimens obtained from chancres having the highest yield rate (63.2%), followed by plasma (49.4%), serum (35.7%), and cerebrospinal fluid or vitreous fluid (18.2%) specimens. Among the 40 fully typed specimens, 11 subtypes of T. pallidum were identified. Subtype 14f/f (18 isolates) was the most common isolates, followed by 14f/c (3), 14b/c (3), and 14k/f (3). Among the isolates examined for macrolide resistance, none had the A2058G or A2059G mutation. In conclusion, we found that type 14 f/f was the most common T. pallidum strain in this multicenter study on syphilis in Taiwan and that none of the isolates exhibited 23S rRNA mutations causing resistance to macrolides.

Molecular subtyping of Treponema pallidum during a local syphilis epidemic in men who have sex with men in Melbourne, Australia

Treponema pallidum is the causative agent of syphilis, a sexually transmitted infection of significant public health importance. Since 2000 there has been a marked increase in the number of cases of syphilis infections notified in Victoria, Australia, with the majority of cases occurring in men who have sex with men (MSM) and the highest incidence being in HIV-infected MSM. The molecular subtyping method described by Pillay et al. (A. Pillay et al., Sex. Transm. Dis. 25:408-414, 1998) has been used in this study to determine the diversity of T. pallidum subtypes circulating locally and to look for any relationship between T. pallidum subtypes and HIV status over a 6-year period (2004 to 2009). Treponema pallidum DNA was detected in 303 patient specimens (n = 3,652), and full subtyping profiles were obtained from 90 of these (from 88 patients). A total of 11 T. pallidum subtypes were identified: types 14e (28, 31.1%), 14d (15, 16.7%), 14k (13, 14.4%), 14p (12, 13.3%), 14i (7, 7.8%) 14b (6, 6.7%), 14l (5, 5.6%), and 12i, 13b, 13i, and 13e (1 each, 1.1%). This study showed a similar level of variation among circulating T. pallidum strains compared with that in other studies using the same methodology. A different mix of strains and different predominating strains have been found at each geographical study location, with type 14e emerging as the predominant local strain in Victoria. There was no detectable trend between T. pallidum subtypes and the specimen collection site or stage of syphilis (where known), nor was there any relationship between particular strains and HIV status.

Detection of the Treponema pallidum gene and variation of treponemal DNA load before and after therapy

We explored a genetic detection method for Treponema pallidum (TP) in the peripheral blood of infected patients to compare the loads of treponemal DNA before and after therapy and to see if this new technique enabled assessment of therapeutic effect and detection of serum resistance. Polymerase chain reaction was used for a qualitative detection of TP DNA in peripheral blood and then a semiquantitative method was adopted to estimate the load of TP DNA in blood, both before and after treatment of syphilis. Among 30 untreated patients, three cases were TP DNA-positive. Among 42 treated patients with demonstrated serum resistance, three cases were TP DNA-positive. Five cases in which the rapid plasma reagin had become negative had no detectable TP DNA in their peripheral blood. The TP DNA load in blood after treatment was significantly lower than that before therapy. We conclude that the detection of TP DNA in peripheral blood of TP-infected patients is not yet sufficiently sensitive, but we observed that TP DNA load declines significantly after treatment.

Genetic diversity in Treponema pallidum: implications for pathogenesis, evolution and molecular diagnostics of syphilis and yaws

Pathogenic uncultivable treponemes, similar to syphilis-causing Treponema pallidum subspecies pallidum, include T. pallidum ssp. pertenue, T. pallidum ssp. endemicum and Treponema carateum, which cause yaws, bejel and pinta, respectively. Genetic analyses of these pathogens revealed striking similarity among these bacteria and also a high degree of similarity to the rabbit pathogen, Treponema paraluiscuniculi, a treponeme not infectious to humans. Genome comparisons between pallidum and non-pallidum treponemes revealed genes with potential involvement in human infectivity, whereas comparisons between pallidum and pertenue treponemes identified genes possibly involved in the high invasivity of syphilis treponemes. Genetic variability within syphilis strains is considered as the basis of syphilis molecular epidemiology with potential to detect more virulent strains, whereas genetic variability within a single strain is related to its ability to elude the immune system of the host. Genome analyses also shed light on treponemal evolution and on chromosomal targets for molecular diagnostics of treponemal infections.

Protocols for detection and typing of Treponema pallidum using PCR methods

Syphilis, caused by Treponema pallidum, is a sexually transmitted disease which was epidemic in Europe between the 15th and 20th century. From 2000 onwards it is worldwide mostly encountered among men who have sex with men but also among women in resource poor setting. Syphilis can easily be treated with penicillin but can become chronic, if left untreated. The disease develops in several stages with ulcerative lesions in the primary stage, and systemic spread to organs via the blood in later stages. Taking swab samples from these ulcerative lesions gives the best options for detection by PCR of T. palillidum. Alternatively blood samples can be analyzed in later stages. If tested positive in screening PCR assays, T. pallidum can also be typed by molecular methods, enabling molecular epidemiology. Different protocols are discussed in this chapter, that include all steps from sample collection, nucleic acid extraction, PCR, and detection. The combination of all steps together determine the final sensitivity and specificity of T. pallidum PCR.

Syphilis: using modern approaches to understand an old disease

Syphilis is a fascinating and perplexing infection, with protean clinical manifestations and both diagnostic and management ambiguities. Treponema pallidum subsp. pallidum, the agent of syphilis, is challenging to study in part because it cannot be cultured or genetically manipulated. Here, we review recent progress in the application of modern molecular techniques to understanding the biological basis of this multistage disease and to the development of new tools for diagnosis, for predicting efficacy of treatment with alternative antibiotics, and for studying the transmission of infection through population networks.

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

BACKGROUND

Syphilis is resurgent in many regions of the world. Molecular typing is a robust tool for investigating strain diversity and epidemiology. This study aimed to review original research on molecular typing of Treponema pallidum (T. pallidum) with three objectives: (1) to determine specimen types most suitable for molecular typing; (2) to determine T. pallidum subtype distribution across geographic areas; and (3) to summarize available information on subtypes associated with neurosyphilis and macrolide resistance.

METHODOLOGY/PRINCIPAL FINDINGS

Two researchers independently searched five databases from 1998 through 2010, assessed for eligibility and study quality, and extracted data. Search terms included "Treponema pallidum," or "syphilis," combined with the subject headings "molecular," "subtyping," "typing," "genotype," and "epidemiology." Sixteen eligible studies were included. Publication bias was not statistically significant by the Begg rank correlation test. Medians, inter-quartile ranges, and 95% confidence intervals were determined for DNA extraction and full typing efficiency. A random-effects model was used to perform subgroup analyses to reduce obvious between-study heterogeneity. Primary and secondary lesions and ear lobe blood specimens had an average higher yield of T. pallidum DNA (83.0% vs. 28.2%, χ(2) = 247.6, p<0.001) and an average higher efficiency of full molecular typing (80.9% vs. 43.1%, χ(2) = 102.3, p<0.001) compared to plasma, whole blood, and cerebrospinal fluid. A pooled analysis of subtype distribution based on country location showed that 14d was the most common subtype, and subtype distribution varied across geographic areas. Subtype data associated with macrolide resistance and neurosyphilis were limited.

CONCLUSIONS/SIGNIFICANCE

Primary lesion was a better specimen for obtaining T. pallidum DNA than blood. There was wide geographic variation in T. pallidum subtypes. More research is needed on the relationship between clinical presentation and subtype, and further validation of ear lobe blood for obtaining T. pallidum DNA would be useful for future molecular studies of syphilis.

Molecular detection of Treponema pallidum sp. pallidum in blood samples of VDRL-seroreactive women with lethal pregnancy outcomes: a retrospective observational study in northern Brazil

INTRODUCTION

Although control measures of maternal and congenital syphilis are available in Brazil, difficulties exist within the healthcare network in providing a laboratory diagnosis of the infection during the prenatal period. The objective of this study was to confirm the presence of Treponema pallidum by PCR in women with positive VDRL serology and lethal pregnancy outcomes, i.e., abortion, stillbirth and neonatal death.

METHODS

A retrospective study was conducted on VDRLseroreactive women with lethal pregnancy outcomes admitted to the Fundação Santa Casa de Misericórdia do Pará (FSCM-PA) between January and July 2004. Serum samples and DNA from whole blood were obtained at the time of screening by the VDRL test. These samples were analyzed by IgG ELISA, IgM FTA-Abs and simple PCR (polA).

RESULTS

During the study period, 0.7% (36/4,912) of women with lethal pregnancy outcomes presented a positive VDRL test. The polAgene was amplified in 72.7% (24/33) of these women, with 55.6% (20/36) and 94.4% (34/36) presenting IgM and IgG antibodies against T. pallidum, respectively. Comparison of these results showed a significant difference, with agreement between the PCR and IgM FTA-Abs results, suggesting that maternal syphilis was an active infection. No basic cause of death of the conceptus was reported in 97.2% (35/36) of cases. Among women who were submitted to the VDRL test during the prenatal period, only four of the nine seroreactive patients underwent treatment.

CONCLUSIONS

The high frequency of syphilis in the group studied indicates the fragility of the service of infection diagnosis, treatment and monitoring, compromising epidemiological control.

Getting the measure of syphilis: qPCR to better understand early infection

Objectives

Until recently, PCR had been used to detect but not quantify Treponema pallidum. To understand infection kinetics of this uncultivable organism, a real-time PCR assay was developed to quantify 47 kDa membrane lipoprotein gene DNA (tpp47).

Methods

Assay specificity was determined against DNA from humans, skin organisms and sexually transmitted pathogens. tpp47 DNA (Nichols strain) was used to construct a standard curve for T pallidum quantification. Blood and ulcer samples were obtained from 99 patients being investigated or screened for syphilis and tpp47 was quantified.

Results

The assay was specific, not cross-reactive with other organisms tested and sensitive, with a detection limit of a single copy of tpp47 DNA. For ulcer samples, the assay was 100% sensitive and 97.14% specific. Sensitivity fell to 34.1% for blood samples but specificity remained high (100%). tpp47 DNA was more commonly detected, and at a higher copy number, in blood of patients with secondary infection (sensitivity 57.89%) compared with primary infection. Quantity of tpp47 DNA was higher in primary infection ulcers, especially in HIV-1-positive patients, than in ulcers persisting into secondary disease.

Conclusions

Quantifying T pallidum provides insight into syphilis infection kinetics: Ulcers of primary disease in HIV-1-positive patients are perhaps more infectious and the presence and load of T pallidum bacteraemia is variable, with a peak in the secondary stage. Quantitative PCR has the potential to map T pallidum infection and to highlight the impact of HIV on syphilis.

Treponema infection associated with genital ulceration in wild baboons

The authors describe genital alterations and detailed histologic findings in baboons naturally infected with Treponema pallidum. The disease causes moderate to severe genital ulcerations in a population of olive baboons (Papio hamadryas anubis) at Lake Manyara National Park in Tanzania. In a field survey in 2007, 63 individuals of all age classes, both sexes, and different grades of infection were chemically immobilized and sampled. Histology and molecular biological tests were used to detect and identify the organism responsible: a strain similar to T pallidum ssp pertenue, the cause of yaws in humans. Although treponemal infections are not a new phenomenon in nonhuman primates, the infection described here appears to be strictly associated with the anogenital region and results in tissue alterations matching those found in human syphilis infections (caused by T pallidum ssp pallidum), despite the causative pathogen's greater genetic similarity to human yaws-causing strains.

Molecular epidemiology of syphilis--San Francisco, 2004-2007

We describe the molecular epidemiology of syphilis in San Francisco (SF) using Treponema pallidum specimens obtained from patients examined at the SF municipal sexually transmitted diseases clinic during 2004-2007. Of 69 specimens, 52 (75%) were subtype 14d9. Single subtype predominance might reflect a closely linked sexual network in SF.

Enhanced molecular typing of treponema pallidum: geographical distribution of strain types and association with neurosyphilis

BACKGROUND

Strain typing is a tool for determining the diversity and epidemiology of infections.

METHODS

Treponema pallidum DNA was isolated from 158 patients with syphilis from the United States, China, Ireland, and Madagascar and from 15 T. pallidum isolates. Six typing targets were assessed: (1) the number of 60‐bp repeats in the acidic repeat protein gene, (2) restriction fragment length polymorphism (RFLP) analysis of T. pallidum repeat (tpr) subfamily II genes, (3) RFLP analysis of the tprC gene, (4) determination of tprD allele in the tprD gene locus, (5) the presence of a 51‐bp insertion between tp0126 and tp0127, and (6) sequence analysis of an 84‐bp region of tp0548. The combination of targets 1 and 2 comprises the Centers for Disease Control and Prevention (CDC) T. pallidum subtyping method.

RESULTS

Adding sequence analysis of tp0548 to the CDC method yielded the most discriminating typing system. Twenty‐five strain types were identified and designated as "CDC subtype/tp0548 sequence type." Type 14d/f was found in samples from 5 of 6 locations. In Seattle, Washington, strain types changed from 1999 through 2008 (P < .001). Twenty‐one (50%) of 42 patients infected with type 14d/f had neurosyphilis compared with 10 (24%) of 41 patients infected with any of the other types combined (P = .02).

CONCLUSION

We describe an enhanced T. pallidum strain typing system that shows biological and clinical relevance.

Methods for typing std pathogens (N. Gonorrhoeae, C. Trachomatis, T. Pallidum)

Phenotypic methods were initially used for bacterial typing yet they have a number of drawbacks limiting their use. Methods of molecular and genetic typing have become wide-spread today. Among these methods, bacterial typing based on multilocus sequence typing (Multilocus Sequence Typing - MLST) has been developing at the fastest rate. However, schemes of molecular and genetic typing of STD pathogens as compared to other bacteria are insufficiently developed, which considerably complicates the planning of measures aimed at the reduction of their spread.

Secondary syphilis in cali, Colombia: new concepts in disease pathogenesis

Venereal syphilis is a multi-stage, sexually transmitted disease caused by the spirochetal bacterium Treponema pallidum (Tp). Herein we describe a cohort of 57 patients (age 18-68 years) with secondary syphilis (SS) identified through a network of public sector primary health care providers in Cali, Colombia. To be eligible for participation, study subjects were required to have cutaneous lesions consistent with SS, a reactive Rapid Plasma Reagin test (RPR-titer > or = 1 : 4), and a confirmatory treponemal test (Fluorescent Treponemal Antibody Absorption test- FTA-ABS). Most subjects enrolled were women (64.9%), predominantly Afro-Colombian (38.6%) or mestizo (56.1%), and all were of low socio-economic status. Three (5.3%) subjects were newly diagnosed with HIV infection at study entry. The duration of signs and symptoms in most patients (53.6%) was less than 30 days; however, some patients reported being symptomatic for several months (range 5-240 days). The typical palmar and plantar exanthem of SS was the most common dermal manifestation (63%), followed by diffuse hypo- or hyperpigmented macules and papules on the trunk, abdomen and extremities. Three patients had patchy alopecia. Whole blood (WB) samples and punch biopsy material from a subset of SS patients were assayed for the presence of Tp DNA polymerase I gene (polA) target by real-time qualitative and quantitative PCR methods. Twelve (46%) of the 26 WB samples studied had quantifiable Tp DNA (ranging between 194.9 and 1954.2 Tp polA copies/ml blood) and seven (64%) were positive when WB DNA was extracted within 24 hours of collection. Tp DNA was also present in 8/12 (66%) skin biopsies available for testing. Strain typing analysis was attempted in all skin and WB samples with detectable Tp DNA. Using arp repeat size analysis and tpr RFLP patterns four different strain types were identified (14d, 16d, 13d and 22a). None of the WB samples had sufficient DNA for typing. The clinical and microbiologic observations presented herein, together with recent Cali syphilis seroprevalence data, provide additional evidence that venereal syphilis is highly endemic in this region of Colombia, thus underscoring the need for health care providers in the region to be acutely aware of the clinical manifestations of SS. This study also provides, for the first time, quantitative evidence that a significant proportion of untreated SS patients have substantial numbers of circulating spirochetes. How Tp is able to persist in the blood and skin of SS patients, despite the known presence of circulating treponemal opsonizing antibodies and the robust pro-inflammatory cellular immune responses characteristic of this stage of the disease, is not fully understood and requires further study.

Molecular subtyping of Treponema pallidum subsp. pallidum in Lisbon, Portugal

The objectives of this study were to evaluate the reproducibility of a molecular method for the subtyping of Treponema pallidum subsp. pallidum and to discriminate strains of this microorganism from strains from patients with syphilis. We studied 212 specimens from a total of 82 patients with different stages of syphilis (14 primary, 7 secondary and 61 latent syphilis). The specimens were distributed as follows: genital ulcers (n = 9), skin and mucosal lesions (n = 7), blood (n = 82), plasma (n = 82), and ear lobe scrapings (n = 32). The samples were assayed by a PCR technique to amplify a segment of the polymerase gene I (polA). Positive samples were typed on the basis of the analysis of two variable genes, tpr and arp. Sixty-two of the 90 samples positive for polA yielded typeable Treponema pallidum DNA. All skin lesions in which T. pallidum was identified (six of six [100%]) were found to contain enough DNA for typing of the organism. It was also possible to type DNA from 7/9 (77.7%) genital ulcer samples, 13/22 (59.1%) blood samples, 20/32 (62.5%) plasma samples, and 16/21 (76.2%) ear lobe scrapings. The same subtype was identified in all samples from the same patient. Five molecular subtypes (subtypes 10a, 14a, 14c, 14f, and 14g) were identified, with the most frequently found subtype being subtype 14a and the least frequently found subtype being subtype 10a. In conclusion, the subtyping technique used in this study seems to have good reproducibility. To our knowledge, subtype 10a was identified for the first time. Further studies are needed to explain the presence of this subtype in Portugal, namely, its relationship to the Treponema pallidum strains circulating in the African countries where Portuguese is spoken.

Molecular characterization of syphilis in patients in Canada: azithromycin resistance and detection of Treponema pallidum DNA in whole-blood samples versus ulcerative swabs

Although detection of Treponema pallidum DNA in whole-blood specimens of syphilis patients has been reported, it is uncertain at what stage of the disease such specimens are most suitable for the molecular diagnosis of syphilis. Also, few studies have directly compared the different gene targets for routine laboratory diagnostic usage in PCR assays. We examined 87 specimens from 68 patients attending two urban sexually transmitted disease clinics in Alberta, Canada. PCR was used to amplify the T. pallidum tpp47, bmp, and polA genes as well as a specific region of the 23S rRNA gene linked to macrolide antibiotic susceptibility. In primary syphilis cases, PCR was positive exclusively (75% sensitivity rate) in ulcerative swabs but not in blood specimens, while in secondary syphilis cases, 50% of the blood specimens were positive by PCR. Four out of 14 (28.6%) of our PCR-positive syphilis cases were found to be caused by an azithromycin-resistant strain(s). Our results confirmed that swabs from primary ulcers are the specimens of choice for laboratory diagnostic purposes. However, further research is required to determine what specimen(s) would be most appropriate for molecular investigation of syphilis in secondary and latent syphilis.

A public health model for the molecular surveillance of HIV transmission in San Diego, California

BACKGROUND

Current public health efforts often use molecular technologies to identify and contain communicable disease networks, but not for HIV. Here, we investigate how molecular epidemiology can be used to identify highly related HIV networks within a population and how voluntary contact tracing of sexual partners can be used to selectively target these networks.

METHODS

We evaluated the use of HIV-1 pol sequences obtained from participants of a community-recruited cohort (n = 268) and a primary infection research cohort (n = 369) to define highly related transmission clusters and the use of contact tracing to link other individuals (n = 36) within these clusters. The presence of transmitted drug resistance was interpreted from the pol sequences (Calibrated Population Resistance v3.0).

RESULTS

Phylogenetic clustering was conservatively defined when the genetic distance between any two pol sequences was less than 1%, which identified 34 distinct transmission clusters within the combined community-recruited and primary infection research cohorts containing 160 individuals. Although sequences from the epidemiologically linked partners represented approximately 5% of the total sequences, they clustered with 60% of the sequences that clustered from the combined cohorts (odds ratio 21.7; P < or = 0.01). Major resistance to at least one class of antiretroviral medication was found in 19% of clustering sequences.

CONCLUSION

Phylogenetic methods can be used to identify individuals who are within highly related transmission groups, and contact tracing of epidemiologically linked partners of recently infected individuals can be used to link into previously defined transmission groups. These methods could be used to implement selectively targeted prevention interventions.

Molecular typing of treponema pallidum clinical strains from Lisbon, Portugal

A molecular system was used to subtype Portuguese Treponema pallidum clinical strains isolated from both skin lesions and blood. The study with this system constitutes the first typing study in a European country. Three T. pallidum subtypes were found: subtypes 14a (50%), 14d (45.2%), and 14f (4.8%). Further studies are needed to better characterize the isolates involved in syphilis outbreaks.

The sequence of the acidic repeat protein (arp) gene differentiates venereal from nonvenereal Treponema pallidum subspecies, and the gene has evolved under strong positive selection in the subspecies that causes syphilis

Despite the completion of the Treponema pallidum genome project, only minor genetic differences have been found between the subspecies that cause venereal syphilis (ssp. pallidum) and the nonvenereal diseases yaws (ssp. pertenue) and bejel (ssp. endemicum). In this paper, we describe sequence variation in the arp gene which allows straightforward differentiation of ssp. pallidum from the nonvenereal subspecies. We also present evidence that this region is subject to positive selection in ssp. pallidum, consistent with pressure from the immune system. Finally, the presence of multiple, but distinct, repeat motifs in both ssp. pallidum and Treponema paraluiscuniculi (the pathogen responsible for rabbit syphilis) suggests that a diverse repertoire of repeat motifs is associated with sexual transmission. This study suggests that variations in the number and sequence of repeat motifs in the arp gene have clinical, epidemiological, and evolutionary significance.

Complete genome sequence of Treponema pallidum ssp. pallidum strain SS14 determined with oligonucleotide arrays

Background

Syphilis spirochete Treponema pallidum ssp. pallidum remains the enigmatic pathogen, since no virulence factors have been identified and the pathogenesis of the disease is poorly understood. Increasing rates of new syphilis cases per year have been observed recently.

Results

The genome of the SS14 strain was sequenced to high accuracy by an oligonucleotide array strategy requiring hybridization to only three arrays (Comparative Genome Sequencing, CGS). Gaps in the resulting sequence were filled with targeted dideoxy-terminators (DDT) sequencing and the sequence was confirmed by whole genome fingerprinting (WGF). When compared to the Nichols strain, 327 single nucleotide substitutions (224 transitions, 103 transversions), 14 deletions, and 18 insertions were found. On the proteome level, the highest frequency of amino acid-altering substitution polymorphisms was in novel genes, while the lowest was in housekeeping genes, as expected by their evolutionary conservation. Evidence was also found for hypervariable regions and multiple regions showing intrastrain heterogeneity in the T. pallidum chromosome.

Conclusion

The observed genetic changes do not have influence on the ability of Treponema pallidum to cause syphilitic infection, since both SS14 and Nichols are virulent in rabbit. However, this is the first assessment of the degree of variation between the two syphilis pathogens and paves the way for phylogenetic studies of this fascinating organism.

Molecular characterization and analysis of a gene encoding the acidic repeat protein (Arp) of Treponema pallidum

The acidic repeat protein (arp) genes from three subspecies of the treponeme Treponema pallidum (T. pallidum subsp. pallidum, Nichols strain; T. pallidum subsp. pertenue, CDC-1 and CDC-2 strains; and T. pallidum subsp. endemicum, Bosnia A strain) were cloned and sequenced. The predicted protein sequence contained a high percentage of glutamic acid, hence the name acidic repeat protein, or Arp. The protein had a potential membrane-spanning domain and a signal peptidase I site. The gene from the Nichols strain of T. pallidum subsp. pallidum contained a set of 14 nearly identical repeats of a 60 bp sequence, which occupied approximately 51 % of the length of the gene. Analyses of arp from laboratory strains showed that the 5' and 3' ends of the genes were conserved, but there was considerable heterogeneity in the number of repeats of this 60 bp sequence. Based on amino acid variations, the 14 sequence repeats could be classified into three types, which were named type I, type II and type III repeats. The type II repeat was the most common in the strains examined. The arp gene of the Nichols strain was subsequently cloned into the expression vector pBAD/TOPO ThioFusion. The expressed protein was detected in a Western blot assay using rabbit immune sera produced against T. pallidum, or synthetic peptides derived from the repeat sequences. Using an ELISA, rapid plasma reagin (RPR) test-positive sera reacted with synthetic peptides derived from the repeat region but not with peptides derived from N and C termini of the Arp protein. These results show that the Arp protein is immunogenic and could prove to be a useful target for serological diagnosis of T. pallidum infection.

Assessment of the kinetics of Treponema pallidum dissemination into blood and tissues in experimental syphilis by real-time quantitative PCR

Little is known about the size and kinetics of treponemal burdens in blood and tissues during acquired or experimental syphilitic infection. We used real-time quantitative PCR to measure Treponema pallidum DNA levels in rabbits infected intratesticularly with the prototype Nichols strain. At the outset, we performed a series of in vitro blood spiking experiments to determine the effect of blood processing procedures on the distribution of treponemes in various blood components. T. pallidum DNA levels in plasma and whole blood were approximately 10-fold higher than those in serum and more than 200-fold greater than those in peripheral blood mononuclear cells (PBMCs). Ten rabbits were inoculated intratesticularly with doses of treponemes ranging from 4 x 10(7) to 2 x 10(8) organisms. In five rabbits, T. pallidum DNA levels were measured sequentially in serum, plasma, whole blood, and PBMCs until sacrifice at peak orchitis, at which time brain, kidney, liver, spleen, and testicles were harvested; blood and organs were also harvested at orchitis from the other five rabbits. T. pallidum DNA was detected in plasma within 24 h postinfection. Treponeme levels in whole blood and blood components increased significantly with the development of peak orchitis. Overall, levels in serum and PBMCs were lower than those in plasma and whole blood; this disparity was particularly marked at early time points. Significantly greater numbers of spirochetes were found in the spleen than in liver, kidney, or brain tissue at the time of sacrifice. Our findings highlight the remarkable capacity of T. pallidum to disseminate from the site of infection to blood and tissues, and they identify the spleen as a prime target for treponemal invasion.

Molecular typing of Treponema pallidum strains from patients with neurosyphilis in Pretoria, South Africa

OBJECTIVE

To evaluate the molecular typing system for Treponema pallidum using cerebrospinal fluid (CSF) specimens obtained from patients with neurosyphilis in Pretoria, South Africa.

METHODS

CSF specimens were collected from 32 men and 18 women with suspected late neurosyphilis. Typing of T pallidum involved PCR amplification and restriction analysis of the tprE, G and J genes and determination of the number of 60 base pair tandem repeats within the arp gene by PCR amplification.

RESULTS

Of 13 typeable specimens, 4 strain types were identified: 2i, 3e, 14a and 17e. Subtype 14a was identified in 7 specimens (53.8%), subtype 3e in 4 specimens (30.7%) and subtypes 17e and 2i in 1 specimen (7.6%) each.

CONCLUSIONS

This study shows that the typing system can be applied to specimens which may contain low numbers of spirochaetes such as CSF.

Molecular subtyping of Treponema pallidum from North and South Carolina

Patients from five clinics in North and South Carolina who had lesions suggestive of primary or secondary syphilis were evaluated using molecular techniques that allow the differentiation of Treponema pallidum strains on the basis of two variable genes, tpr and arp. Lesion samples were screened for the presence of T. pallidum DNA using PCR for polA, which represents a segment of the polymerase I gene that is unique to the spirochete. Twenty-seven of 154 lesion samples were found to contain T. pallidum, 23 of which had typeable DNA. Seven molecular subtypes were found (10f, 12f, 13f, 14f, 14g, 15f, and 16f); one to four subtypes were identified at each clinic. Subtype 14f was found in 52% of the typeable specimens and was distributed in four of the five clinics. Subtype 16f was found in 22% of specimens and was concentrated at one clinic. Further data are needed to define the role of this technique in examining the epidemiology of syphilis.

Detection of the 47-kilodalton membrane immunogen gene of Treponema pallidum in various tissue sources of patients with syphilis

Polymerase chain reaction (PCR) was used to detect the 47-kDa immunogen gene of Treponema pallidum in peripheral blood mononuclear cells (PBMCs), skin lesions, and serum, but less consistently in purified granulocytes or ejaculates of patients with manifest and latent syphilis. Therefore, skin lesions and PBMCs may serve as the most reliable sources for a PCR-based diagnosis of syphilis.

Syphilis 2001--a palaeopathological reappraisal

The origin and subsequent spread of the treponematoses, especially that of venereal syphilis, has been the subject of considerable scientific attention. Various theories were put forth and palaeopathological specimens were used for their validation in recent times. One influential contribution was the paper by Baker & Armelagos in 1988. Numerous new findings and results on both sides of the Atlantic call for a new evaluation of the available osseous material. A review of the recent literature leads to the suggestion of a worldwide distribution of non-venereal treponemal disease since the emergence of Homo and to a first epidemic outbreak of venereal syphilis in Europe of the late 15th and the early 16th century, which was a time of change and enormous sexual liberty. Old World specimens with pathological alterations attributed to venereal syphilis and dated to precolumbian times seem to invalidate the Columbian theory and call for a more differentiated analysis of the phenomenon of syphilis than a theory based on a single factor can provide. With the help of molecular methods which now allow a positive identification of Treponema pallidum pallidum, causative agent of venereal syphilis, in palaeopathological material, it seems possible to elucidate the matter of origin and spread of syphilis further and to evaluate previous diagnoses of treponemal disease.

Molecular typing of Treponema pallidum in South Africa: cross-sectional studies

We evaluated a molecular subtyping system for Treponema pallidum for its ability to differentiate between strains obtained from male patients with primary syphilis in South Africa. Of 201 T. pallidum-positive specimens, 161 were typeable, revealing 35 subtypes. The unique subtypes identified in Durban, Cape Town, and Carletonville and the total number of subtypes suggested that the strain population was very diverse and varied geographically.

Amplification of the DNA polymerase I gene of Treponema pallidum from whole blood of persons with syphilis

Previous reports suggest that Treponema pallidum bacteremia occurs in persons with syphilis exposure ('incubating syphilis') and in persons with primary or secondary syphilis. During a recent syphilis outbreak, whole blood samples from 32 persons with suspected syphilis or syphilis exposure were screened using polymerase chain reaction (PCR) to amplify the DNA polymerase I gene (polA) of T. pallidum. Of the 32 samples, polA was amplified from 13 (41%). Of these 13, three were determined to have incubating syphilis; two had primary or secondary syphilis and eight had latent syphilis. This study demonstrates that spirochetemia can occur throughout the course of T. pallidum infection.