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Background: Clostridium difficile infections (CDI) in humans range from asymptomatic carriage to life-threatening intestinal disease. Findings on C. difficile in various animal species and an overlap in ribotypes (RTs) suggest potential zoonotic transmission. However, the impact of animals for human CDI remains unclear., Methods: In a large-scale survey we collected 1,447 fecal samples to determine the occurrence of C. difficile in small companion animals (dogs and cats) and their owners and to assess potential epidemiological links within the community. The Germany-wide survey was conducted from July 2012-August 2013. PCR ribotyping, Multilocus VNTR Analysis (MLVA) and PCR detection of toxin genes were used to characterize isolated C. difficile strains. A database was defined and logistic regression used to identify putative factors associated with fecal shedding of C. difficile., Results: In total, 1,418 samples met the inclusion criteria. The isolation rates for small companion animals and their owners within the community were similarly low with 3.0% (25/840) and 2.9% (17/578), respectively. PCR ribotyping revealed eight and twelve different RTs in animals and humans, respectively, whereas three RTs were isolated in both, humans and animals. RT 014/0, a well-known human hospital-associated lineage, was predominantly detected in animal samples. Moreover, the potentially highly pathogenic RTs 027 and 078 were isolated from dogs. Even though, C. difficile did not occur simultaneously in animals and humans sharing the same household. The results of the epidemiological analysis of factors associated with fecal shedding of C. difficile support the hypothesis of a zoonotic potential., Conclusions: Molecular characterization and epidemiological analysis revealed that the zoonotic risk for C. difficile associated with dogs and cats within the community is low but cannot be excluded.

Cats and dogs live in more than 20 % of German households and the contact between these pets and their owners can be very close. Therefore, a transmission of zoonotic pathogens may occur. To investigate whether zoonotic research questions can be examined in the context of population-based studies like the German National Cohort (GNC), two studies on different study populations were conducted as part of the feasibility tests of the GNC. The aim of the first study was to quantify the actual exposure of participants of the GNC to cats and dogs. In the second study summarised here the feasibility of the sampling of cats and dogs by their owners was tested. To quantify the exposure of participants of the GNC to cats and dogs 744 study participants of the Pretests of the GNC were asked whether they had contact with animals. Currently 10 % have a dog and 14 % have a cat in their household. These figures confirm that a large proportion of the German population has contact with pets and that there is a need for further zoonoses research. To establish the collection of biological samples from cats and dogs in the context of large-scale population-based studies feasible methods are needed. Therefore, a study was conducted to test whether pet owners can take samples from their cats and dogs and whether the quality of these samples is comparable to samples taken by a qualified veterinarian. A total of 82 dog and 18 cat owners were recruited in two veterinary practices in Hannover and the Clinic for Small Animals at the University of Veterinary Medicine in Hannover. Sampling instructions and sample material for nasal and buccal swabs, faecal samples and, in the case of cat owners, a brush for fur samples, were given to the pet owners. The pet owners were asked to take the samples from their pets at home and to send the samples by surface mail. Swab samples were cultured and bacterial growth was quantified independent of bacterial species. The growth of Gram-positive and Gram-negative bacteria from samples taken by the veterinarian and the pet owners were compared. For Gram-positive bacteria the agreement of laboratory results was 71 % for nasal swabs and 78 % for oral swabs while for Gram-negative bacteria the agreement of laboratory results was 55 % for nasal swabs and 87 % for oral swabs. In conclusion it has been shown that participants of the GNC are exposed to cats and dogs and that the sampling of cats and dogs by their owners is a feasible method which can be a useful tool for zoonoses research in population-based studies.