RESEARCH ARTICLE Open Access Preliminary studies on isolates of Clostridium difficile from dogs and exotic pets Sara Andrés-Lasheras 1 , Inma Martín-Burriel 2 , Raúl Carlos Mainar-Jaime 1 , Mariano Morales 1,3 , Ed Kuijper 4 , José L. Blanco 5 , Manuel Chirino-Trejo 6 and Rosa Bolea 1* Abstract Background: Clostridium difficile infection (CDI) is recognised as an emerging disease in both humans and some animal species. During the past few years, insights into human CDI epidemiology changed and C. difficile is also considered as an emerging community-acquired pathogen. Certain ribotypes (RT) are possibly associated with zoonotic transmission. The objective of this study was to assess the presence of C. difficile in a population of pets and to characterise the isolates. Results: Faecal samples from a total of 90 diarrhoeic dogs and 24 from exotic animal species (both diarrhoeic and non-diarrhoeic) were analysed. Clostridium difficile was isolated from 6 (6.7%) dogs and one reptile sample (4.2%). Four (66.7%) of the six dog strains were capable of producing toxins. Four known different RTs were detected in dogs (010, 014, 123 and 358) and a new one was found in a faecal sample of an exotic animal. This new RT isolate was negative for all toxin genes tested and belonged to sequence type 347 which has been proposed as a Clade-III member. Importantly, two dog strains showed a stable resistance to metronidazole (initial MIC values: 128 and 48 μg/ml). Conclusions: The results obtained in this study suggest the implementation of antimicrobial susceptibility surveillance programs to assess the prevalence of metronidazole resistance in dogs; molecular studies to elucidate C. difficile metronidazole resistance mechanisms are warranted. Based on the similarity between the ribotypes observed in dogs and those described in humans, the zoonotic transmission should be further explored. Furthermore, exotic animals have shown to harbor uncommon C. difficile strains which require further genomic studies. Keywords: Clostridium difficile, Dog, Exotic, Metronidazole-resistant, PCR-ribotyping, MLST Background Clostridium difficile is a bacterium capable of producing enteric disease in different animal species included humans. Toxigenic C. difficile strains are the most com- mon cause of antibiotic-associated diarrhoea in people from developed countries through the synthesis of toxins A and B, its main virulence factors [1]. The epidemi- ology of C. difficile has changed in the last 15 years and it is now recognised as an emerging pathogen in both humans and animals. It is also considered an emerging community-acquired pathogen likely associated with a zoonotic and/or foodborne transmission [2]. Animals are an important source of many infectious dis- eases for humans. About 75% of emerging infectious dis- eases are zoonoses [3], and it is thought that pets could be implicated in the transmission of C. difficile to humans since similar genotypes have been recovered from them and humans [4]. Among the strains isolated from dogs, there are several ribotypes of international interest, such as RT078, RT014/020 and RT045 [5]. Likewise, exotic ani- mals can act as vectors of many zoonotic diseases, includ- ing enteric diseases, and several zoonotic outbreaks have been associated with the trade of this type of animal spe- cies (either in a legal or illegal way) as their international trade has increased recently [6]. However, there is limited * Correspondence: rbolea@unizar.es 1 Departamento de Patología Animal, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), 50013 Zaragoza, Spain Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Andrés-Lasheras et al. BMC Veterinary Research (2018) 14:77 https://doi.org/10.1186/s12917-018-1402-7