Piglet Models of Acute or ChronicClostridium difficileIllness

Abstract

We have examined the piglet model for CDI in humans since swine are naturally susceptible to C. difficile. The piglet is a reproducible model for acute or chronic CDI with characteristic pseudomembranous colitis (PMC). Germfree piglets were consistently and extensively colonized when orally challenged with the human 027/BI/NAP1 strain, establishing an infectious dose-age relationship. This allowed a demarkation between acute fatal and chronic models. The clinical manifestations of disease inclusive of gastrointestinal and systemic symptoms and characteristic mucosal lesions in the large bowel including PMC are described. Additionally, we demonstrate the presence of toxins in feces, body fluids and serum, and a significant elevation of IL-8 in animals with severe disease. We conclude that piglets infected with C. difficile mimic many of the key characteristics observed in humans with CDI, and are suitable animals in which to investigate the role of virulence attributes, drug efficacy and evaluation of vaccine candidates.

The roles of toxin A and toxin B inClostridium difficileinfection

“…1A). Lung lesions in these piglets differed, however, as the lungs displayed the areas of cranialventral consolidation we have previously noted in piglets inoculated with C. difficile spores 8 ( Fig. 1D).…”

“…8 The piglets were divided into 3 groups and recombinant TcdA and/or TcdB (rTcdA or rTcdB) were administered via intraperitoneal injection. The rTcdA and rTcdB were expressed in Bacillus megaterium and purified in our laboratory using previously described methods.…”

“…All of these piglets developed signs of severe systemic illness, including respiratory distress, that we have observed in C. difficile infected piglets previously and have associated with systemic toxin circulation. 8,11 The 2 piglets that received rTcdB only had no clinical signs of disease 24 h after administration, so a second dose of 10 μg rTcdB was administered. Again, the piglets developed no signs of illness, so the dose was increased to 30 μg and then 100 μg of rTcdB.…”

“…Gnotobiotic piglets are used as an animal model of choice as we have found them to most closely compare with human C. difficile infection, as compared with the mouse or hamster models. 8 Gnotobiotic piglets mimic the intestinal microflora altered state that makes human patients more susceptible to C. difficile infection, without the need for antibiotic treatment before inoculation, and piglets also develop a similar extent and range of lesions in the large intestine and clinical signs of disease compared with humans. …”

Clostridium difficile Infection

“…For these reasons, the model is suitable to study colonization, transmission and persistence phenotypes 38,148,149 . A piglet model is of particular interest to study C. difficile strains that are problematic in both animal and human populations 13,35,150 . In vitro gut models have been developed to study interactions of C. difficile with therapeutics in the context of a complex microbiome 13,151,152 .…”