Experimental inoculation and nose-to-nose transmission of Clostridioides difficile between weaned piglets.

In piglets, Clostridioides (C.) difficile infection presents mostly subclinical manifestation. As this agent became important in veterinary medicine due to a hypothesis of zoonosis, the objective of this study was to evaluate the transmission of C. difficile by nose-to-nose contact in young piglets. Six 20-day-old piglets were separated into three groups (infected, sentinel and control), and distributed in different isolation cabinets which allowed nose-to-nose contact only between infected and sentinel groups. The challenged group received an inoculum 106 CFU/mL of C. difficile 096 by oropharyngeal route. Rectal swab samples were daily collected for microbiological and molecular analysis. Euthanasia of all piglets was performed 18 days after challenge to evaluate anatomical, histological and microbiological lesions of the organs of these animals. The challenged and sentinel groups showed clinical signs of infection and genes encoding TcdB were detected by conventional PCR in both groups, confirming the transmission of the pathogen from the challenged to the sentinel piglets. At necropsy, tonsil, liver, spleen, mesenteric lymph nodes, ileocolic lymph nodes, jejunum, ileum, proximal colon, distal colon and cecum were collected for microbiological analysis; lesions were observed varying in degree and intensity. This study demonstrated a novel route of transmission of C. difficile between young piglets, which was proven to occur by nose-to-nose contact.