Title: Prevalence of PCR ribotypes among Clostridium difficile isolates from pigs, calves and other species Running Title: PCR ribotypes of Clostridium difficile isolates

PCR ribotypes were obtained for 144 Clostridium difficile isolates from neonatal pigs. Porcine isolates comprised four PCR ribotypes but one, ribotype 078, predominated (83%). This was also the most common ribotype (94%) among 33 calf isolates, but was rarely identified in other species. Numerous epidemiologic investigations of human Clostridium difficile-associated disease (CDAD) have employed phenotyping and genotyping to better understand transmission patterns and risk factors (3, 7, 8). In contrast, few studies have typed isolates from animals or environments where they are housed. Most have attempted to test the hypothesis that humans acquire C. difficile from animals, and the results have varied (1, 9). We know little about the epidemiology of C. difficile within animal populations and uncertainties persist as to the relationships, if any, of such animal strains to those associated with human CDAD. CDAD has emerged as a significant economic concern for swine producers but little is known about transmission patterns in hog operations (11, 14). The objective of this study was to assess the strain types occurring among various species with CDAD. PCR-ribotyping was used due to its proven discriminatory power, reproducibility, and relative simplicity (2). Different strains of C. difficile possess different numbers of rRNA genes and the intergenic sequences vary in size, yielding PCR products of distinct sizes for each designated ribotype. Isolates from five host species were examined, but porcine isolates were most numerous (Table 1). Neonatal pigs were sampled in Iowa, Ohio, AC CE PT ED on A uust 0, 2017 by gest ht://jcm .sm .rg/ D ow nladed fom