in equidae necropsied in Northwestern France, between 2019 and 2021.

Abstract

an anaerobic, spore-forming enteropathogen, is less studied in animals than in humans despite its importance in One Health. We evaluatedoccurrence, diversity, circulation, and virulence in French Equidae (= 100) after their necropsy in northwestern France, from 2019 to 2021. We systematically recovered all cecal contents and any watery intestinal contents. We isolatedstrains, determined their toxin gene profile by PCR, and established their PCR-ribotype according to the WEBRIBO database. We also performed free toxin detection. Twenty-seven Equidae were positive forand 20 had a toxigenic strain, including one animal co-colonized by a non-toxigenic strain. Toxigenic isolates belonged to eight already described ribotypes: (i) 078 and 126 (toxin genes of wild-type size:), (ii) 005, 012, 020, AI-53, and FR227 (), and (iii) 017 (). Non-toxigenic isolates were of ribotypes 009, 035, and 439. Ribotypes 017 and 009 were predominant (= 5). In two cases, Equidae of the same premises shared the same ribotype, either 020 or 009. Free toxins were detected in four animals: they displayed signs of diarrhea and aof ribotype 126 (= 1) or 017 (= 3) as the only detected enteropathogen, suggesting ainfection (CDI). Three of them had received antibiotics. Two had died from an entero-toxic infection, for whichribotype 017 was the only identified cause. French Equidae displayed common pathogenicand ribotype 017 was highly virulent. These findings are of concern from a One Health perspective.IMPORTANCE, a major enteropathogen widely disseminated in the environment, is a One Health issue. Animals are raising concern as human contamination sources. Equidae are in close contact with humans and also develop-antibiotic and healthcare-associated CDIs. The systematic survey of Equidae necropsied from 2019 to 2021 in the leading horse breeding region in France revealed that 20% harbored pathogenic strains. These belonged to clinically important ribotypes, raising the possibility of cross-species, zoonotic or anthropo-zoonotic transmission. Free toxins, which are rarely tested in animals, were detected in four animals with signs of diarrhea and a toxigenicas the only identified enteropathogen, suggesting CDI. In two of them,ribotype 017 was the only identified cause of entero-toxic disease and death. French Equidae could play a role in the dissemination of pathogenicand notably ribotype 017. They should be surveilled carefully from a One Health perspective.