Histological Effects of the Challenge with Clostridium Difficile in Weaned Pig

Infection with C. difficile may have subclinical signs and light manifestations of disease; its transmission is fecal-oral route, considered as the principal way of contamination. As bacterial infections have negative impact, on the roster, this study has relation with the ways of transmission of C. difficile in swine. This study was to evaluate the transmission of C. difficile via aerogen using PCR and histological section of tissue.

Special isolation booths were used. Six weaned pigs (15 days old) were obtained from a free C. difficile farm. Were installed in couples in a safe cabinet and microbiologically monitored daily during 18 days. Cabinets were placed in a straight line (cabinet 1 - control pigs, cabinet 2 - inoculated and cabinet 3 – sentinel pig). This way air flows from the control to the sentinel. The inoculum was C. difficile VPI A/B 10463, with 7.21 x 10⁸ CFU/mL. An aliquot of 3 mL was administered orally into the pharyngeal region to the pigs of group 2. Control and sentinel pigs received only sterile BHI broth (3 mL) as placebo. Were evaluated for clinical sings of infection, after this period were euthanized and necropsied for lesion evaluation. Liver, spleen, tonsils, mesenteric lymph nodes and ileocolic, jejunum, ileum, proximal and distal colon and cecal contents of the three groups were collected for microbiological and histological analysis. Fragments were placed into BHI, incubated 37°C for 48h in anaerobiosis for clostridial growth. DNA extractions were performed by boiling technique. The PCR reactions were directed for the detection of genes encoding toxins tcdA and tcdB with annealing temperature of 52°C for 1 min. For histopathological analysis fragments were collected from the same portions and located in bottles with 10% formalin.

PCR technic confirmed C. difficile in jejunum and colon of the infected group, meanwhile in control and sentinel groups samples were negative for this pathogen. In the histological analysis control and sentinel group did not presented apparent lesions in selected portions. Piglets of the infected group showed the liver, spleen, tonsils and lymph nodes reactive, besides the spleen that presented lymphoid rarefaction of white pulp, and calcification in interstice of the tonsils and apoptosis with invasion of the lymphocytes epithelium. The intestinal crypts of the mucosa showed hyperplasia of the caliciforms cells and mucus. Among animals of the infected group, enteritis traits and denudation of the villi with reactivity in Pleyer plates were observed.

It was concluded that there was no infection of the sentinel group via aerogen, confirmed by PCR and histologic analysis.

Disclosure of Interest: None Declared.