Toxinotype V<i>Clostridium difficile</i>in Humans and Food Animals

Abstract

Clostridium diffi cile is a recognized pathogen in neonatal pigs and may contribute to enteritis in calves. Toxinotype V strains have been rare causes of human C. diffi cileassociated disease (CDAD). We examined toxinotype V in human disease, the genetic relationship of animal and human toxinotype V strains, and in vitro toxin production of these strains. From 2001 through 2006, 8 (1.3%) of 620 patient isolates were identifi ed as toxinotype V; before 2001, 7 (<0.02%) of 6,000 isolates were identifi ed as toxinotype V. Six (46.2%) of 13 case-patients for whom information was available had community-associated CDAD. Molecular characterization showed a high degree of similarity between human and animal toxinotype V isolates; all contained a 39bp tcdC deletion and most produced binary toxin. Further study is needed to understand the epidemiology of CDAD caused by toxinotype V C. diffi cile, including the potential of foodborne transmission to humans. R ecent evidence suggests that the epidemiology of Clostridium diffi cile-associated disease (CDAD) is increasing in incidence and severity (1-3). These changes are due, at least in part, to the emergence of a more virulent C. diffi cile strain, designated NAP1 (based on its pulsed-fi eld gel electrophoresis [PFGE] pattern), BI (by restriction endonuclease analysis [REA]), toxinotype III (by PCR characterization of the pathogenicity locus), and 027 (by PCR ribotyping) (4). However, the emergence of BI/NAP1/027 may not be solely responsible for changes in CDAD epidemiology, and the origin of this and other virulent strains is