Streptococcus didelphis infection in free-ranging white-eared opossum (Didelphis albiventris) and Brazilian common opossum (Didelphis aurita): pathology, microbiologic, and genomic characterization

Marsupials of the genus Didelphis are highly adapted to urban environments and are widely distributed in the Americas. Streptococcus didelphis is a bacterium that has been isolated from, and associated with disease, in the Virginia opossum (Didelphis virginiana) and the white-eared opossum (Didelphis albiventris). This study describes pathological changes associated with S. didelphis infection in white-eared opossums (Didelphis albiventris) and Brazilian common opossums (Didelphis aurita) as well as microbiological and genomic characterization of isolates. Ten opossums underwent necropsy and had ulcerative dermatitis of probable traumatic origin had S. didelphis was isolated from cutaneous lesions (n = 16) or systemic sites (n = 4). In contrast, 34 free-ranging opossums that were captured had negative culture results for S. didelphis from nasal swabs. Other lesions in opossums naturally infected with S. didelphihs included splenitis (7/10), myocarditis (6/10), interstitial nephritis and pyelonephritis (7/10), and myositis (4/10). Most isolates were susceptible to the antimicrobial drugs tested and none of them were able to form biofilm in vitro. Whole genome analysis of six isolates revealed no resistance determinants, virulence factors or plasmids, and the isolates showed high genomic similarity.