Syphilis is a multistage sexually transmitted disease caused by Treponema pallidum ssp. pallidum. In the Czech Republic, there are around 700-800 new syphilis cases annually, continuously increasing since 2012. This study analyzed a total of 1228 samples from 2004 to 2022. Of the PCR-positive typeable samples (n = 415), 68.7% were fully-typed (FT), and 31.3% were partially-typed. Most of the identified isolates belonged to the SS14-clade and only 6.3% were the Nichols-like cluster. While in the beginning of sample collection isolates have been macrolide-susceptible, recent isolates are completely resistant to macrolides. Among the FT samples, 34 different allelic profiles (APs) were found. Most of the profiles (n = 27) appeared just once in the Czech population, while seven profiles were detected more than twice. The most frequent APs belonged to two separate groups of SS14-like isolates, including group of 1.3.1 (ST 1) and 1.26.1 (ST 25) profiles, and the second group containing 1.1.8 (ST 3), 1.1.1 (ST 2), and 1.1.3 (ST 11) (representing 57.5%, and 25.3% of all detected APs, respectively). Both groups consistently differed in 6 nucleotide positions in five genes (TP0150, TP0324, TP0515, TP0548, and TP0691) coding amino-acid replacements suggesting that one or more of these differences could be involved in the higher success of the first group.

• MeSH
• Alleles * MeSH
• Adult MeSH
• Genotype MeSH
• Middle Aged MeSH
• Humans MeSH
• Macrolides pharmacology   MeSH
• Multilocus Sequence Typing * MeSH
• Syphilis * microbiology   epidemiology   genetics   MeSH
• Treponema pallidum * genetics   isolation & purification   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• Macrolides MeSH

In this work, we determined that Treponema pallidum subsp. pallidum (TPA) DAL-1 (belonging to Nichols-like group of TPA strains) grew 1.53 (± 0.08) times faster compared to TPA Philadelphia 1 (SS14-like group) during in vitro cultivations. In longitudinal individual propagation in rabbit testes (n = 12, each TPA strain), infection with DAL-1 manifested clinical symptoms (induration, swelling, and erythema of testes) sooner than Philadelphia 1 infection, which resulted in a significantly shorter period of the experimental passages for DAL-1 (median = 15.0 and 23.5 days, respectively; p < 0.01). To minimize the confounding conditions during rabbit experiments, the growth characteristics of DAL-1 and Philadelphia 1 strains were determined during TPA co-infection of rabbit testes (n = 20, including controls). During two weeks of intratesticular co-infection, DAL-1 overgrew Philadelphia 1 in all twelve testes, regardless of inoculation ratio and dose (median of relative excess DAL-1 multiplication = 84.85×). Moreover, higher DAL-1 to Philadelphia 1 inoculum ratios appeared to increase differences in growth rates, suggesting direct competition between strains for available nutrients during co-infection. These experiments indicate important physiological differences between the two TPA strains and suggest growth differences between Nichols-like and SS14-like strains that are potentially linked to their virulence and pathogenicity.

• MeSH
• Rabbits MeSH
• Syphilis microbiology   pathology   MeSH
• Testis microbiology   metabolism   MeSH
• Treponema pallidum * MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Bejel (endemic syphilis) is a neglected non-venereal disease caused by Treponema pallidum subsp. endemicum (TEN). Although it is mostly present in hot, dry climates, a few cases have been found outside of these areas. The aim of this work was the sequencing and analysis of TEN isolates obtained from "syphilis patients" in Cuba, which is not considered an endemic area for bejel. Genomes were obtained by pool segment genome sequencing or direct sequencing methods, and the bioinformatics analysis was performed according to an established pipeline. We obtained four genomes with 100%, 81.7%, 52.6%, and 21.1% breadth of coverage, respectively. The sequenced genomes revealed a non-clonal character, with nucleotide variability ranging between 0.2-10.3 nucleotide substitutions per 100 kbp among the TEN isolates. Nucleotide changes affected 27 genes, and the analysis of the completely sequenced genome also showed a recombination event between tprC and tprI, in TP0488 as well as in the intergenic region between TP0127-TP0129. Despite limitations in the quality of samples affecting breadth of sequencing coverage, the determined non-clonal character of the isolates suggests a persistent infection in the Cuban population rather than a single outbreak caused by imported case.

• MeSH
• Disease Outbreaks MeSH
• Treponemal Infections * epidemiology   MeSH
• Humans MeSH
• Nucleotides MeSH
• Syphilis * epidemiology   MeSH
• Treponema pallidum genetics   MeSH
• Treponema MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Nucleotides MeSH

BACKGROUND: Treponema pallidum subspecies pallidum (TPA) and subsp. endemicum (TEN) are the causative agents of syphilis and bejel, respectively. TEN shows similar clinical manifestations and is morphologically and serologically indistinguishable from TPA. Recently, bejel was found outside of its assumed endemic areas. Using molecular typing we aimed to discover bejel and characterize circulating TPA types among syphilis cases with Surinamese, Antillean and Dutch ethnicity in Amsterdam. METHODS: DNA was extracted from 137 ulcer swabs, which tested positive in the in-house diagnostic PCR targeting the polA gene. Samples were collected between 2006 and 2018 from Surinamese, Antillean and Dutch patients attending the Amsterdam STI clinic. Multilocus sequence typing was performed by partial sequence analysis of the tp0136, tp0548 and tp0705 genes. In addition, the 23S rRNA loci were analyzed for A2058G and A2059G macrolide resistance mutations. RESULTS: We found 17 distinct allelic profiles in 103/137 (75%) fully typed samples, which were all TPA and none TEN. Of the strains, 82.5% were SS14-like and 17.5% Nichols-like. The prevalence of Nichols-like strains found in this study is relatively high compared to nearby countries. The most prevalent types were 1.3.1 (42%) and 1.1.1 (19%), in concordance with similar TPA typing studies. The majority of the TPA types found were unique per country. New allelic types (7) and profiles (10) were found. The successfully sequenced 23S rRNA loci from 123/137 (90%) samples showed the presence of 79% A2058G and 2% A2059G mutations. CONCLUSIONS: No TEN was found in the samples from different ethnicities residing in Amsterdam, the Netherlands, so no misdiagnoses occurred. Bejel has thus not (yet) spread as a sexually transmitted disease in the Netherlands. The strain diversity found in this study reflects the local male STI clinic population which is a diverse, mixed group.

• MeSH
• Alleles MeSH
• Genes, Bacterial * MeSH
• Adult MeSH
• Ethnicity statistics & numerical data   MeSH
• Humans MeSH
• Syphilis epidemiology   ethnology   microbiology   MeSH
• DNA Barcoding, Taxonomic MeSH
• Treponema pallidum classification   genetics   pathogenicity   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Netherlands Antilles MeSH
• Netherlands MeSH
• Suriname MeSH

Syphilis, caused by Treponema pallidum subsp. pallidum (TPA), remains an important public health problem with an increasing worldwide prevalence. Despite recent advances in in vitro cultivation, genetic variability of this pathogen during infection is poorly understood. Here, we present contemporary and geographically diverse complete treponemal genome sequences isolated directly from patients using a methyl-directed enrichment prior to sequencing. This approach reveals that approximately 50% of the genetic diversity found in TPA is driven by inter- and/or intra-strain recombination events, particularly in strains belonging to one of the defined genetic groups of syphilis treponemes: Nichols-like strains. Recombinant loci were found to encode putative outer-membrane proteins and the recombination variability was almost exclusively found in regions predicted to be at the host-pathogen interface. Genetic recombination has been considered to be a rare event in treponemes, yet our study unexpectedly showed that it occurs at a significant level and may have important impacts in the biology of this pathogen, especially as these events occur primarily in the outer membrane proteins. This study reveals the existence of strains with different repertoires of surface-exposed antigens circulating in the current human population, which should be taken into account during syphilis vaccine development.

• Keywords
• Treponema pallidum subsp. pallidum, culture-independent bacterial enrichment, direct whole genome sequencing, recombination-driven diversity, syphilis,
• Publication type
• Journal Article MeSH

BACKGROUND: Pathogenic treponemes related to Treponema pallidum are both human (causing syphilis, yaws, bejel) and animal pathogens (infections of primates, venereal spirochetosis in rabbits). A set of 11 treponemal genome sequences including those of five Treponema pallidum ssp. pallidum (TPA) strains (Nichols, DAL-1, Mexico A, SS14, Chicago), four T. p. ssp. pertenue (TPE) strains (CDC-2, Gauthier, Samoa D, Fribourg-Blanc), one T. p. ssp. endemicum (TEN) strain (Bosnia A) and one strain (Cuniculi A) of Treponema paraluisleporidarum ecovar Cuniculus (TPeC) were tested for the presence of positively selected genes. METHODOLOGY/PRINCIPAL FINDINGS: A total of 1068 orthologous genes annotated in all 11 genomes were tested for the presence of positively selected genes using both site and branch-site models with CODEML (PAML package). Subsequent analyses with sequences obtained from 62 treponemal draft genomes were used for the identification of positively selected amino acid positions. Synthetic biotinylated peptides were designed to cover positively selected protein regions and these peptides were tested for reactivity with the patient's syphilis sera. Altogether, 22 positively selected genes were identified in the TP genomes and TPA sets of positively selected genes differed from TPE genes. While genetic variability among TPA strains was predominantly present in a number of genetic loci, genetic variability within TPE and TEN strains was distributed more equally along the chromosome. Several syphilitic sera were shown to react with some peptides derived from the protein sequences evolving under positive selection. CONCLUSIONS/SIGNIFICANCE: The syphilis-, yaws-, and bejel-causing strains differed relative to sets of positively selected genes. Most of the positively selected chromosomal loci were identified among the TPA treponemes. The local accumulation of genetic variability suggests that the diversification of TPA strains took place predominantly in a limited number of genomic regions compared to the more dispersed genetic diversity differentiating TPE and TEN strains. The identification of positively selected sites in tpr genes and genes encoding outer membrane proteins suggests their role during infection of human and animal hosts. The driving force for adaptive evolution at these loci thus appears to be the host immune response as supported by observed reactivity of syphilitic sera with some peptides derived from protein sequences showing adaptive evolution.

• MeSH
• Genes, Bacterial * MeSH
• Adaptation, Biological * MeSH
• Adult MeSH
• Genomics MeSH
• Genotype * MeSH
• Humans MeSH
• Young Adult MeSH
• Selection, Genetic MeSH
• Syphilis microbiology   pathology   MeSH
• Treponema pallidum classification   genetics   isolation & purification   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Young Adult MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

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.

• MeSH
• Alleles MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Drug Resistance, Bacterial genetics   MeSH
• DNA, Bacterial genetics   MeSH
• Adult MeSH
• Genotype MeSH
• Humans MeSH
• Young Adult MeSH
• Multilocus Sequence Typing * MeSH
• RNA, Ribosomal, 23S genetics   MeSH
• Syphilis genetics   microbiology   pathology   MeSH
• Treponema pallidum genetics   pathogenicity   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• DNA, Bacterial MeSH
• RNA, Ribosomal, 23S MeSH