No indication for tissue tropism in urogenital and anorectal Chlamydia trachomatis infections using high-resolution multilocus sequence typing.

Bart Versteeg,Martijn S Van Rooijen,Maarten F Schim Van Der Loeff,Henry Jc De Vries,Sylvia M Bruisten

doi:10.1186/1471-2334-14-464

Abstract

BackgroundPrevious studies showed that C. trachomatis strains found in MSM are different from those in heterosexuals. This study investigates whether the differences in strain distribution between MSM and heterosexuals are due to tissue tropism.MethodsC. trachomatis positive samples were collected from MSM (anorectal) and women (anorectal, cervical, vaginal, pharyngeal) visiting the STI outpatient clinic of Amsterdam between 2008 and 2013. All samples were typed using multilocus sequence typing (MLST). Epidemiological data were derived from electronic patient records.ResultsWe obtained full MLST data for C. trachomatis from 207 MSM and 185 women, all with anorectal infections. Six large clusters were identified of which 3 consisted predominantly of samples from women (89%-100%), whereas the other 3 consisted predominantly of samples from MSM (97%-100%). Furthermore, we obtained full MLST data from 434 samples of 206 women with concurrent infections at multiple anatomical locations. No association was observed between C. trachomatis cluster and the anatomical location of infection.ConclusionWe found no indication for tissue tropism in urogenital, pharyngeal and anorectal C. trachomatis infections. Combined with results from previously conducted studies, we hypothesize that MSM and heterosexuals have different distributions of C. trachomatis strains due to their separate sexual networks.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2334-14-464) contains supplementary material, which is available to authorized users.

Highlights

Previous studies showed that C. trachomatis strains found in men who have sex with men (MSM) are different from those in heterosexuals
We found that C. trachomatis infections circulating among women belonged to 3 heterogeneous clusters of various sizes, whereas the majority of infections found among MSM belonged to 3 homogeneous clusters
Previous studies hypothesized that pathogenrelated factors such as tissue tropism could explain the distinct distribution of C. trachomatis strains circulating among MSM and heterosexual populations, but lacked data to test this hypothesis [7,15]

Summary

Introduction

Previous studies showed that C. trachomatis strains found in MSM are different from those in heterosexuals. C. trachomatis is currently divided into 15 main genovars, according to immunotyping of the major outer membrane protein (MOMP) or analysis of the coding ompA gene [5] These 15 genovars can be grouped into ocular genovars A to C, anogenital genovars D to K, and LGV genovars L1 to L3 [6]. Most of the studies using ompA typing demonstrated that the majority of infections among heterosexuals involved genovars D, E, and F, while the majority of infections among MSM involved genovars D, G, and J [7,8,9,10,11] They demonstrated that genovar prevalence varied by anatomical site: genovar G is more commonly found in the anorectal tract, whereas other genovars are more common in the urogenital tract [8,10,12,13]

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Results

Discussion

Conclusion