Fatal Systemic Infection Caused by Multidrug-Resistant Clostridioides difficile in a Domestic Rabbit: A Comprehensive Case Analysis.

Background/Objectives: Rabbit farming in Romania is increasingly important for providing high-quality meat, yet productivity is frequently threatened by enteric diseases, particularly in young animals. Among bacterial etiologies, Clostridioides difficile (C. difficile) has emerged as a significant gastrointestinal pathogen, with findings suggestive of systemic dissemination and public health implications. This study aimed to investigate a fatal case of C. difficile infection in a farmed rabbit and to characterize the pathogen's microbiological, toxigenic, and antimicrobial profile. Methods: An 11-month-old male German Giant Spotted rabbit presenting acute diarrhea, anorexia, and rapid deterioration after unsupervised administration of enrofloxacin and sulfaquinoxaline was submitted postmortem. Necropsy was performed, and samples from cecum, colon, liver, spleen, mesenteric lymph nodes, lungs, and femoral bone marrow were collected. Microbiological analysis included selective culture on CCFA medium, ELISA for toxin A and B detection, MALDI-TOF MS identification, PCR confirmation, and antimicrobial susceptibility testing with the VITEK 2 system. Histopathological examination was conducted on intestinal and parenchymal tissues. Results: Necropsy revealed severe congestion and necrosis of the cecal and colonic mucosa, hepatomegaly, splenic congestion, and petechial hemorrhages. C. difficile was isolated from intestinal sites, confirmed as toxigenic by ELISA and PCR. Histopathology showed necrotizing colitis with epithelial desquamation, fibrin deposition, and heterophilic infiltration. The strain exhibited resistance to clindamycin, ampicillin, and tetracycline, with susceptibility to vancomycin, linezolid, and tigecycline. Conclusions: This case demonstrates that C. difficile can cause severe disease in rabbits, particularly following antimicrobial-induced dysbiosis. The findings underscore the importance of prudent antibiotic use, monitoring of toxigenic strains in rabbit populations, and implementation of preventive strategies to mitigate health risks in both animals and potentially humans.