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

This study aimed to investigate the molecular diversity of a bacterium, Streptococcus equi subsp. zooepidemicus (S. zooepidemicus), typically found in horses’ lower genital tract and often causing endometritis in mares. The research took place in Buenos Aires province, Argentina, assessing specific strains of S. zooepidemicus taken from mares suffering from endometritis.

About the Research

• The research centers around a bacterium, S. zooepidemicus. Often found in mares, this bacterium can cause a form of inflammation of the inner lining of the uterus, known as endometritis.
• The researchers sought to examine the different kinds of the bacterium, or ‘strains’, extant in mares within the Buenos Aires province of Argentina.

Methodology

• It was conducted over a period of twelve years (2005 – 2017), with 30 bacterial isolates taken from infected mares studied.
• The team used a technique known as multilocus sequence typing (MLST), to identify genotypes, or genetic variations within the bacterial species.
• An eBURST algorithm – goeBURST – was used to elucidate the relationships between these different genotypes and track their evolution over time.

Results and Findings

• A total of 26 unique sequence types (STs) were identified. These are distinct genomic strains within the bacterial species, differentiated by different alleles, or alternative forms of a gene, present within their DNA.
• Of these 26 STs, only 11 had been previously identified in horses; the rest were newly discovered in this study.
• No significant link could be found between the STs identified in Argentina and those documented globally. Consequently, it was inconclusive whether the same S. zooepidemicus strain circulates within the equine population of Argentina.
• Interestingly, genotypes were also found across different countries, samples, and species, suggesting no adaptation specific to the host or tissue location. This further highlighted the bacterium’s role as an opportunistic pathogen—one that takes advantage of certain situations to cause disease.
• A significant observation was the identical genotype found in both the uterus and vagina or clitoris of the same mare, further emphasizing the bacterium’s versatility.