High prevalence of the epidemic Clostridium difficile PCR ribotype 078 in Iberian free-range pigs

Previous studies in intensively raised piglets have detected a high prevalence of the epidemic Clostridium difficile PCR ribotype 078. In this article we present a longitudinal survey of C. difficile colonisation in a population of Iberian pigs reared under a free-range system. A total of 160 faecal samples from 20 piglets belonging to different litters were obtained by weekly sampling. C. difficile was recovered from samples collected at different times throughout the survey from a 90% of piglets, resulting in an overall prevalence of 25.6% in the studied samples. Most positive samples (75.6%) came from ≤ 15-day animals, but some piglets shed C. difficile even on day +50. All isolates were ribotype 078, harboured toxin-encoding genes and showed in vitro resistance to several fluoroquinolones. A majority of isolates (80.5%) were also high-level resistant to ertapenem, and four metronidazole heteroresistant isolates (9.8%) were detected. In conclusion, Iberian free-range pigs can be a potential reservoir of epidemic antimicrobial-resistant strains of C. difficile, showing a prevalence rate similar to that found for intensively raised animals.