Observation on the morphology of contagious equine metritis bacterial colonies isolated from infected pony mares

In uterine or cervical specimens obtained from pony mares infected with streptomycin-resistant contagious equine metritis bacteria, several colonies of the bacteria which differed in morphologic characteristics were recognized during their primary isolation on Eugon chocolate agar and tryptose chocolate agar plates. The differences were usually not observed until plates were incubated 10 to 15 days. On Eugon chocolate agar plates, smooth colony, sandy colony with rings, and colony with blebs were recognized. On tryptose chocolate agar plates, only a round smooth convex colony was observed. By scanning electron microscopy, colonies consisted of coccal, coccobacillary, and bacillary forms. Only one type of colony was isolated from any mare.