Novel Molecular Type of Clostridium difficile in Neonatal Pigs, Western Australia

Michele M. Squire, Glen P. Carter, Kate E. Mackin, Anjana Chakravorty, Torbjörn Norén, Briony Elliott, Dena Lyras, and Thomas V. Riley

Author affiliations: The University of Western Australia, Nedlands, Western Australia, Australia (M.M. Squire, B. Elliott, T.V. Riley); Monash University, Clayton, Victoria, Australia (G.P. Carter, K.E. Mackin, A. Chakravorty D. Lyras); Örebro University Hospital, Örebro, Sweden (T. Norén); PathWest Laboratory Medicine, Nedlands (T.V. Riley)

Abstract

Clostridium difficile causes neonatal enteritis in piglets; strains of PCR ribotype 078 are most commonly identified. We investigated C. difficile prevalence in piglets in Australia and isolated a novel strain with a unique pathogenicity locus. In a mouse infection model, this strain produced more weight loss than did a ribotype 078 strain.

Clostridium difficile is the causative agent of severe enteritis (“scouring”) in neonatal piglets 1–7 days of age throughout Canada, the United States, and Europe (1). Although deaths attributable to C. difficile infection (CDI) generally are low because of good stockmanship, piglets that survive CDI remain 10%–15% underweight on average and take additional time to wean (2).
Colonization frequency of C. difficile in scouring piglets is as high as 52%; this rate declines to 4% by 2 months of age (3). C. difficile is also commonly found in feces from apparently healthy piglets, which contributes to environmental contamination. Widespread air and surface contamination of the piggery environment with C. difficile, presumably in the form of long-surviving spores, may play a role in the epidemiology of CDI in pigs and subsequent community-acquired infection in humans (4).
In Europe and the United States, the genotypes of C. difficile isolates that cause disease in humans and production animals overlap, particularly PCR ribotype 078, which predominates in pigs worldwide. This ribotype is increasing in prevalence and associated with severe community-acquired CDI in humans geographically located near pig farms (5). C. difficile has also been found in retail food, including meat products, seafood, and vegetables (6).
C. difficile in piglets in Australia has not been systematically investigated, despite reports of idiopathic enteritis nationwide. It is likely that that C. difficile strains in piglets in Australia are different from those found in the rest of the world because of Australia’s geographic isolation, strict quarantine laws regarding importation of livestock, and low human population and pig density. We studied C. difficile prevalence in scouring neonatal piglets and evaluated a novel strain of C. difficile isolated from these piglets by using multiple identification methods.