Sudden death with pseudomembranous fibrinonecrotic enteritis in a zoo-housed hippopotamus (Hippopotamus amphibius): predominant isolation and genomic characterization of Clostridium perfringens type A.

IMPORTANCE: Clostridium perfringens type A (CPA) is a common intestinal commensal, but it has been implicated in peracute fatal enteritis under predisposing conditions. Although clostridial enteric disease is well characterized in domestic species, reports in captive megaherbivores are rare. In addition, genomic data for CPA isolates from zoo-housed wildlife remain scarce, limiting comparative epidemiologic investigations. CASE PRESENTATION: A 40-year-old female zoo-housed hippopotamus (Hippopotamus amphibius) was found dead without prior clinical signs. Necropsy revealed diffuse pseudomembranous fibrinonecrotic and hemorrhagic enteritis. Histopathology showed acute mucosal necrosis with an overlying fibrinonecrotic pseudomembrane and abundant intralesional bacilli. Aerobic culture yielded Escherichia coli without major virulence genes, whereas anaerobic culture yielded abundant β-hemolytic colonies. Multiplex toxinotyping polymerase chain reaction identified the predominant anaerobe as CPA (plc-positive only). Whole-genome sequencing yielded a 3.25-Mb draft assembly comprising 37 putative chromosomal contigs (3.20 Mb total) and one 48-kb putative plasmid contig. In silico screening detected plc, pfoA, colA, cloSI, multiple sialidase/hexosaminidase genes, and predicted antimicrobial resistance determinants [mprF and tetA(P)/tetB(P)]. CONCLUSIONS AND RELEVANCE: To our knowledge, this is the first genomic characterization of a CPA isolate from an adult hippopotamus, providing a reference for zoo-based surveillance and outbreak investigations. Clostridial-type fibrinonecrotic-hemorrhagic enteritis should be considered in the differential diagnosis of sudden death in adult zoo-housed hippopotami.