Multi-Locus Sequence typing of Treponema pallidum in male patients with genital ulcers in a public STD clinic in South Brazil: a new alelle and almost complete macrolide resistance

Abstract

Objective: Considering the absence of data on genotyping of <i>T. pallidum</i> in Brazil, We aimed at study its strains and resistance to macrolides in genital ulcers suggestive of syphilis.
Methods: Men with genital ulcers suggestive of syphilis were invited to participate. Samples were collected with a dry cotton swab and immersed in 0.9% NaCl solution. The detection was done by PCR amplification of a 260 bp of the tpp47 gene. PCR product was analyzed by electrophoresis in 2% agarose gel containing 0.05% ethidium bromide. Positive PCR samples were analyzed by MLST (sequencing of chromosomal loci TP0136, TP0548, and TP0705). Mutation A2058G and A2059G on the 23S rRNA gene was evaluated by nested PCR. DNA sequencing was analyzed using the Bioedit software (Tom Hall, USA). Genotyping was performed using the online platform PubMLST (Grillová scheme).
Results: All subjects were residents of Porto Alegre and ranged from 19 to 66 years old. Of the 43 samples, 32 were T. pallidum PCR positive. Thirty strains were available for genotyping and belonged to either the Clonal Complex SS14-like (73.3%) or Nichols-like (20%). Three complete MLST profiles were identified (1.3.1;9.7.3 and 28.7.3), and a new allele (x.x.11) at the locus TP0705 was identified in one sample. Only one sample did not have the 2058 mutation in the 23S rRNA gene.
Conclusion: Our study identified genetic diversity in <i>T. pallidum</i> DNA using MLST with allele variants for TP0136, TP0548, and TP0705, including a new allele, the only sample characterized as genotypic susceptible to macrolides. All the others (over 95%) samples presented the A2058G mutation in the 23S rRNA gene, which causes resistance to macrolides. Improving local understanding of T. pallidum is crucial to effective prevention and care.