Streptococcus equi zooepidemicus
Keywords: Streptococcus equi var. zooepidemicus, infertility, equine
This image shows a culture of Streptococcus equi var. zooepidemicus on blood agar. The author's record is devoid of details for this image but it was probably isolated from a mare with endometritis because it is a common genital pathogen in mares.
Streptococcus zooepidemicus is also a common commensal bacterium, easily isolated from normal horses. This is important to bear in mind when cultures are positive for Streptococcus zooepidemicus because contamination from the perineal area will often produce false positive cultures.
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The image shows beta hemolysis (complete hemolysis) around the colonies of bacteria. This is due to an exotoxin produced by many Streptococcal species. Some of those species cause partial hemolysis (alpha hemolysis) as well, but not Streptococcus equi var. zooepidemicus
Note: It is common for clinicians to refer Streptococcus equi var. zooepidemicus by its short form, Streptococcus zooepidemicus, forgetting perhaps that this bacterium is one of two subspecies of Streptococcus equi . The other is Streptococcus equi var. equi , the well known cause of Strangles in horses. Streptococcus equi var. zooepidemicus is a gram-positive coccoid bacterium occurring in pairs or long chains on stained preparations. It is usually sensitive to penicillin and its derivatives.
