Physiological characterisation of Corynebacterium uterequi associated with pregnancy complications in mares

• Published in: Veterinary microbiology Vol. 273; p. 109522
• Main Authors: Koroleva, Elizaveta, Steffen, Heidi Christa, Bosch, Caylin, Flemming, Leonard, Botha, Alfred
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2022
• Subjects: Corynebacterium uterequi; Endometritis; Equine; Mare; Reproduction; Corynebacterium uterequi; Reproduction; Equine; Mare; Endometritis
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2022.109522

Increasing cases of equine infertility and early embryonic loss in the Western Cape, South Africa, were documented in recent years. These appeared to be associated with Corynebacterium uterequi isolated from the uteri of infected mares. The purpose of this study was, therefore, to investigate the physiology and potential pathogenicity of this bacterium. Histopathological analyses were conducted on five mares suffering from reproductive complications, and from which Corynebacterium strains were detected on culture of uterine swabs. The histopathology revealed that the mares suffered from various forms of endometritis, suggesting a potential role of Corynebacterium strains in the disease. An isolate from one of the biopsies, and 11 other tentatively identified C. uterequi isolates from the urogenital tracts of other mares, which all had a history of pregnancy complications, were subsequently identified using molecular techniques and characterised based on environmental stress tolerance, enzyme profiles, antibiotic susceptibility and ability to form biofilms. It was found that representatives of C. uterequi possessed several virulence-associated characteristics, including trypsin and urease activity, as well as the ability to form weakly adherent monoculture biofilms. Several isolates displayed resistance to trimethoprim-sulfamethoxazole. In conclusion, this study provided some insight into the general physiology and pathogenic potential of C. uterequi, and points to the possible role of C. uterequi in the onset of equine pregnancy complications. Moreover, the ability to form biofilms suggests the potential for chronic infection, which was observed in 60% of the mares. Further research, however, is needed to implicate C. uterequi as an equine pathogen. •High prevalence of Corynebacterium strains was detected in uteri of problem mares.•An association between C. uterequi and pregnancy complications was observed.•A polyphasic approach was used to characterise the physiology of C. uterequi.•Antibiotic resistance was observed in some strains of C. uterequi.•Virulence factors were detected in C. uterequi.