Research Article: 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

Date Published: May 31, 2019

Publisher: Public Library of Science

Author(s): Eliška Vrbová, Linda Grillová, Lenka Mikalová, Petra Pospíšilová, Radim Strnadel, Eliška Dastychová, Martina Kojanová, Miluše Kreidlová, Daniela Vaňousová, Filip Rob, Přemysl Procházka, Alena Krchňáková, Vladimír Vašků, Vladana Woznicová, Monika Dvořáková Heroldová, Ivana Kuklová, Hana Zákoucká, David Šmajs, Antonella Marangoni.


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.

Partial Text

Treponema pallidum subsp. pallidum (TPA) is an unusual bacterial pathogen [1] that causes syphilis, a chronic venereal disease in humans. Each year, there are about 5.6 million new cases worldwide [2–3]. In recent years, there have been approximately 700–800 cases of syphilis per year in the Czech Republic, a country having about 10.5 million citizens (data provided by the Institute of Health Information and Statistics of the Czech Republic). Most of the cases were among men having sex with men (MSM), promiscuous individuals, or sex-workers [4].

We examined 675 clinical samples collected from 2004–2017 from four hospitals in the two largest cities in the Czech Republic (2 hospitals in Brno and 2 hospitals in Prague). While all samples were tested against TP0705, TP0136, and TP0548 between 2014–2017, data for TP0136 and TP0548 came from clinical samples collected between 2004 and 2013 as part of previous studies [4, 19] and were retested in locus TP0705. We found 281 samples to be positive and typeable, i.e., at least one locus TP0136, TP0548, or TP0705, was amplified and sequenced. The majority of the typed samples were swabs from primary or secondary syphilis lesions (n = 231) and the rest were from whole blood samples (n = 47) and tissue samples (n = 3) taken post mortem. Most of the samples (86.48%) belonged to the SS14-like genetic group, while only 2.13% belonged to the Nichols-like genetic group. The remaining 32 samples (11.39%) were not classified as SS14-like or Nichols-like because of selective positivity for locus TP0705 which does not contain informative sites for discriminating between these two genetic groups. Clinical characteristics of patients are summarized in Table 1.

In this study, we examined 675 samples collected from patients suspected of having syphilis between 2004 to 2017 from four clinics, two in Brno and two in Prague. Almost one-half of the samples were PCR-positive and typeable (n = 281, 41.6%). In comparison with other MLST studies [15–17], this study represents largest collection of typed samples. Moreover, a long time period of collecting samples allowed to discover over two dozens of allelic profiles including highly diverse allele in the TP0136 locus.