It has also been reported that the cdt-III genes were located on a plasmid harboring the cnf2 gene [20], whereas cdt-V was chromosomal and carried by bacteriophage [25], suggesting that detection of the cnf2 gene could be one of the genetic markers to differentiate cdt-III and cdt-V

gene-positive strains. Indeed, all the 25 strains with cdt-III were also positive for cnf2. However, 7 out of the 52 cdt-V gene-positive strains from cattle also contained cnf2 and this gene arrangement has not yet been reported. Go6983 datasheet Since homology between cdt-III and cdt-V genes is very high (cdtA, 97.3%; cdtB, 99.7%; cdtC, 96.5%) [4], it is difficult to differentiate the cdt-III and cdt-V genes by PCR, suggesting that some of the cdt-III and cdt-V genes might have been misidentified. In the present study, three PCR primer sets, cdt-IIIABC, cdt-Vup, cdt-Vdown, each PF-6463922 targeting the internal region of cdt-III[10], the 5′ and 3′ flanking regions of cdt-V[17], failed in producing specific amplicon in 1, 9 and 3 strains, respectively, out of the 58 CTEC-V and 1 CTEC-III and V (Table 2). However, the type-specific BAY 11-7082 cost PCR developed in this study using two primer sets each targeting cdt-III or cdt-V (Figure 1) could produce specific amplicon either for cdt-III or cdt-V. The cdt-III- and cdt-V-specific PCR designed in this study is more reliable to differentiate these genes and to generate more

precise epidemiological data. In fact, using the type-specific PCR, we identified a both cdt-III and cdt-V gene-positive E. coli strain. To our knowledge, this is the first report to describe the isolation of CTEC-III and V strain. Since reservoir for STEC has been identified to be ruminant such as cattle and this

study also indicates that reservoir for CTEC could be the same, similar genes for adhesion might be associated with colonization of both STEC and CTEC. In addition to the eaeA gene, saa, iha, lpfA O113 and ehaA genes have also been reported to encode putative adhesins in STEC O157 and non-O157 [26–29]. Recently Wu et al. [22] described a probable association of these 4 genes, in particular lpfA O113 and ehaA genes, with the long-term STEC shedding from cattle. When virulence gene profiling, in particular, for adhesin were analyzed in this study, 86 and 83% strains from cattle and swine, respectively, were found to be positive for lpfA O113 Avelestat (AZD9668) and ehaA genes, while 100% stx gene-positive CTEC isolates were all positive for saa, lpfA O113 , ehaA and iha genes. Furthermore, almost all of them were positive for cdt-III or cdt-V whereas 2 strains were positive for cdt-I genes. In this study, 97% of cdt genes detected in the feces of cattle was cdt-III or cdt-V whereas only 2 and 1% of cdt genes were cdt-I and cdt-IV, respectively. Clark et al. [13] also reported that the cdt-III genotype was more prevalent in animal strains although the majority of cdt genotypes isolated from humans was cdt-I and cdt-IV[10].