Introduction; Clostridium difficile is a spore-forming bacterium associated with neonatal diarrhea in pigs worldwide. Recently, the incidence of C. difficile associated disease (CDAD) has been significantly increasing in veterinary medicine and the infected farms show increased pre-weaning mortality and poor growth rates. The purpose of this study was to reproduce CDAD with Korean C. difficile strains using SPF minipigs and to provide pathologic evaluation of CDAD in neonatal pigs.
Materials and Methods; Ten SPF mini pigs were enrolled in the study and they were given minimum colostrum. At approximately, six hours of age, eight piglets were randomly assigned to a challenge group. And they were orally inoculated with swine-origin C. difficile Korean field isolate (ribotype 078). Two control pigs were sham-inoculated. All pigs were individually housed and randomly assigned to necropsy at 72 (five piglets) or 108 (five piglets) hours post infection. Tissue samples from intestines (cecums and colons) and intestinal contents were collected for histopathologic evaluation, bacterial culture, and toxin detection.
Results; C. difficile was isolated from all inoculated pigs and the sequential isolation rate of C. difficile from rectal swabs was increased. All isolates recovered from pigs were ribotype 078, the same as their challenge isolate. However, there is no other enteropathogens causing diarrhea were not detected at all. Grossly, mesocolonic edema and pasty-to-watery contents in colons were observed in inoculated piglets. Classical microscopic lesions with suppurative fibrinous typhlocolitis and mucosal erosion were observed. Those pathological lesions were being severe as time goes on. Moreover, the severity of pathological lesions was associated with the level of toxins.
Conclusions; In conclusion, the results demonstrate that Korean strain can cause gross and microscopic lesions. Furthermore, provided evidences have potential to be an effective challenge model for pathogenesis and intervention strategies of CDAD.