Sabrina Defourny, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise

Streptococcus gallolyticus is a Gram-positive bacterium commonly regarded as a commensal of the gastrointestinal tract of humans and animals, while infections in wildlife are rarely reported and its pathogenic role remains poorly understood. The Marsican brown bear (Ursus arctos marsicanus) is an endangered subspecies with a core population of about 60 individuals, mainly restricted to the Abruzzo, Lazio and Molise National Park (PNALM), Italy. This report describes a case of systemic S. gallolyticus infection in a Marsican brown bear found dead within the PNALM. The carcass was submitted to the Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise of Teramo to determine the cause of death and exclude poisoning or illegal killing. RX examination, performed at OVUD of Teramo, ruled out the presence of fractures, bullets or metallic foreign bodies. External inspection revealed multiple parallel skin lesions affecting the head, neck, thorax, and limbs; several were penetrating and associated with edema, hemorrhage, and severe muscle lacerations, findings consistent with intraspecific aggression. Necropsy showed sero-hematic effusion, fibrinous pleurisy, and multifocal adhesions between the lung and thoracic wall; the pericardium was thickened and covered with fibrinous material. Advanced autolysis prevented histopathological evaluation. S. gallolyticus was isolated from multiple organs (lung, kidney, heart, bone marrow, and muscle), in pure culture from the heart and bone marrow, supporting systemic infection; identification was achieved by MALDI-TOF. Virologic, parasitological, and toxicological tests were negative. Traumatic skin and muscle injuries likely acted as predisposing factors for opportunistic infection. This case highlights the importance of integrated diagnostic approaches in wildlife mortality investigations and underscores the value of systematic sanitary surveillance for the conservation of endangered wildlife populations.