Streptococcus equi subsp. zooepidemicus: High molecular diversity of Argentinian strains isolated from mares with endometritis

Abstract

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a mucosal commensal of the lower genital tract inhorses and is the most isolated bacterium causing endometritis in mares. The aim of this study was to determinethe molecular diversity of S. zooepidemicus obtained from endometritis in mares in Buenos Aires province,Argentina. Thirty isolates obtained from the uterus of mares in 2005 and 2017 were studied. The MLST schemewas applied to identify the Argentinian genotypes and the clonal relationships and patterns of evolutionarydescent were identified using the eBURST algorithm – goeBURST. Twenty six different Sequence types (STs) wereidentified, being only 11 of them previously reported in horses and also, from several host species and tissues.The other 15 STs were reported in Argentinian reproductive strains of mares in our study for the first time. Thegenotypes obtained from uterus in Argentina were not evenly distributed when all the published S. zooepidemicusSTs were analysed, thus, it was not possible to establish that the same lineage circulates in our equine population.The fact that the identified genotypes were also reported in other countries, diverse samples and host speciessuggest that there is not a host, and an anatomical niche adaptation. Finally, the isolation of the same genotype inthe vagina/clitoris and the uterus of the same mare highlights the versatility of S. zooepidemicus and its role as anopportunistic pathogen.