EXPERIMENTAL-INFECTION OF NEWBORN PIGLETS WITH YERSINIA-ENTEROCOLITICA - AN ANIMAL-MODEL OF ENTERITIS

Newborn, colostrum-deprived Large White piglets infected with a human isolate of Yersinia enterocolitica biotype 4 serotype 0:3 were used as an animal model of yersiniosis. Within 3 hours of birth and before be ing fed, 14 piglets were inoculated orogastrically with 10 mi of bacte rial suspension containing about 3 X 10(10) colony forming units of Y. enterocolitica, followed by 10 mi of 10% NaHCO3 solution. A further 1 4 litter mates acted as controls. The animals were reared on an artifi cial milk formula and humanely killed at 3 or 5 days after infection. Of the 14 infected piglets, 11 became anorexic, five vomited and 13 de veloped diarrhoea. Yersinia enterocolitica was isolated from their fae ces and small intestinal contents. Body weight gains and the plasma gl ucose concentrations were significantly lower in the infected piglets than in the controls. Damage to the mucosa was observed in the whole g astro-intestinal tract, but was more severe in the small intestine and caecum. Micro-abscesses surrounding bacteria were present at the base of the villi in all parts of the small intestine, particularly in the distal ileum. Lesions were present in the small intestine in all infe cted piglets by day 3 and were more extensive by day 5. The liver was damaged by day 5, but not day 3. Similar lesions were seen in the muco sa of the stomach in one of six piglets at 3 days and in two of eight piglets at 5 days. It is hypothesised that the hypoacidity in the newb orn stomach, as well as the administration of the NaHCO3 solution, may have produced favourable conditions for bacterial invasion.