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Introduction: In humans Clostridium (C.) difficile infections (CDI) can vary from symptomless carriage to life-threatening intestinal disease. The recent changes in epidemiology of CDI with an increasing incidence and severity are of particular concern. Although virulent strains affecting humans have also been isolated from various animal species, epidemiological data on C. difficile in companion animals are scarce, limiting the risk assessment of possible interspecies transmission.
Objectives: This study aimed to collect first national data on occurrence and genotypic variation of C. difficile in dogs, cats and their owners and define risk factors associated with colonization or CDI.
Materials & Methods: From July 2012 to August 2013, a Germany-wide survey was conducted sampling companion animals and their owners. Capillary gel electrophoresis based PCR ribotyping, Multilocus VNTR Analysis (MLVA) and PCR detection of toxin genes A, B and the binary toxin were used to characterise isolated C. difficile strains.
Results: A total of 1,435 faecal samples could be acquired from 415 different households with 40.7% of human and 59.3% of animal origin. The C. difficile isolation rates were 2.91% (17/584) and 2.94% (25/851) for human and animal samples, respectively. Typing revealed twelve resp. eight different PCR ribotypes in isolates from humans resp. companion animals. Three of the animal ribotypes could also be isolated from human samples (014/0, 010 and the highly virulent ribotype 078). Moreover ribotypes 027 and 078 were isolated in dogs. These ribotypes are considered highly virulent in humans. Within two households identical ribotypes were isolated from two partner animals (in both cases 014/0), whereas no C. difficile pair from owner and pet sharing the same household could be detected. The risk assessment revealed known risk factors for colonization or CDI in humans (antibiotic intake and age). In companion animals risk factors positively associated with C. difficile colonization/CDI were the contact to a human suffering from diarrhoea, intake of antibiotics or proton pump inhibitors, age, acute disease, inappetence, and diarrhoea.
Conclusion: C. difficile isolation rates are low in companion animals and their owners in Germany. Well known human ribotypes including virulent ribotypes 027 and 078 also occur in
dogs and suggest a common infection source, zoonotic transmission or both. Future case-control studies should be implemented to get insight into the risk of zoonotic C. difficile infections.