This study reports the first fatal case of multidrug-resistant Escherichia coli (MDR-E. coli) causing respiratory and septicemic infections in rabbits in Romania, highlighting the dual threat of antimicrobial resistance to veterinary and public health. Through systematic necropsy, bacterial isolation, and molecular analysis, the research confirms the strain's high virulence and multidrug resistance, offering critical warnings for antimicrobial stewardship, biosecurity, and One Health monitoring.
Literature Overview
This article, 'Multidrug-Resistant Escherichia coli Causing Respiratory and Systemic Infections in Domestic Rabbits: First Report in Romania,' published in the journal *Antibiotics*, reviews a clinical case involving an 8-month-old German Spotted Giant rabbit from a rural Romanian farm. The rabbit succumbed to acute respiratory distress and rapid death due to MDR-E. coli infection. The study confirms the presence of multiple virulence genes (fimH, papC, iutA, ompA) and resistance genes (blaCTX-M, blaTEM, tetA, sul1) through necropsy, bacterial culture, MALDI-TOF mass spectrometry, Congo red staining, and molecular PCR assays. It underscores the potential role of rabbits in spreading multidrug-resistant pathogens and raises urgent concerns about antimicrobial use and biosecurity in rural farming systems.
Background Knowledge
Escherichia coli is a common intestinal commensal but can become pathogenic under specific conditions, causing respiratory infections, septicemia, and systemic inflammation. Widespread antimicrobial use has led to global challenges in both human and veterinary medicine. Virulence factors such as IutA (iron uptake receptor), FimH (type I fimbriae adhesin), and OmpA (outer membrane protein) enhance bacterial colonization and immune evasion, facilitating systemic infections. Resistance genes can spread through horizontal gene transfer, accelerating antimicrobial failure. This study focuses on rabbit infection models under poor housing conditions, revealing potential links between environmental stressors, antimicrobial misuse, and pathogen dissemination. Respiratory diseases in rabbit farms are increasingly common, with limited treatment options due to MDR strains, emphasizing the model's relevance to public health and veterinary research. Rabbits are also widely used in vaccine development, antimicrobial testing, and toxicology studies, making this research applicable to both veterinary and human disease models.
Research Methods and Experiments
A postmortem examination was conducted on an 8-month-old German Spotted Giant rabbit. Lung, tracheal, and bone marrow samples were collected for bacterial culture using Columbia blood agar and MacConkey media. Morphological and biochemical identification combined Congo red staining and MALDI-TOF mass spectrometry. Antimicrobial susceptibility testing employed the VITEK 2 system to determine minimum inhibitory concentrations (MICs) of multiple antibiotics. PCR screening targeted virulence genes (fimH, papC, iutA, ompA) and resistance genes (blaCTX-M, blaTEM, tetA, sul1). The study further assessed the clinical implications of multidrug resistance and its colonization capacity in respiratory and systemic tissues.
Key Conclusions and Perspectives
Research Significance and Prospects
This work highlights the role of rabbits in multidrug-resistant pathogen transmission, urging improved farm-level surveillance and biosecurity. Future studies should investigate horizontal gene transfer mechanisms, host immune evasion pathways, and alternative interventions (e.g., phage therapy, probiotics). Additionally, rabbits as translational models in infectious disease, immunology, and antimicrobial research warrant further exploration to bridge veterinary and human medicine.
Conclusion
This study documents the first fatal case of respiratory and systemic infection caused by MDR-E. coli in Romania, emphasizing the dual threat of antimicrobial resistance to veterinary and public health. Findings suggest that poor housing conditions exacerbate pathogen virulence and transmission, with environmental stressors (e.g., inadequate ventilation, ammonia exposure, overcrowding) potentially promoting pathogen colonization and immune suppression. Virulence genes (fimH, papC, iutA, ompA) indicate enhanced adhesion and iron uptake, with potential host-jumping risks. The strain's resistance to conventional antimicrobials necessitates molecular diagnostics, resistance gene screening, and biosecurity measures. It also advocates for One Health surveillance and alternative therapies (e.g., phage therapy, probiotics, natural antimicrobials) to reduce antimicrobial dependence. Future research should prioritize gene mobility, host-pathogen interactions, and the translational value of rabbit models in infectious disease studies.
