, 2008) and reflecting the fact that the agent has not been approved for use in veterinary practice in China. Although phenotypic resistance may be

overestimated in our analysis because isolates showing intermediate susceptibility were considered resistant, we believe that the results reflect the general trend observed Tyrosine Kinase Inhibitor Library concentration with E. coli strains isolated from pigs. Other studies have reported that E. coli isolates from cattle and swine fall into phylogenetic groups A and B1, whereas avian pathogenic E. coli isolates mainly belonged to groups A, D, and B1 (Johnson et al., 2008; Ghanbarpour et al., 2010) and human pathogenic isolates predominantly belonged to phylogenetic groups B2 and D (Johnson et al., 2002, 2003). In agreement with some of these findings, we found that E. coli isolates

from diseased swine were mostly from phylogenetic groups A and B1. Ten VGs associated with swine E. coli were detected in all isolates. The high prevalence of Stx2e (63%) in this study was in agreement with other studies from swine E. coli isolates (da Silva et al., 2001; Fratamico et al., 2004). The prevalence of AIDA-I (9%) and EAST1 (64%) in the study was similar to that in previous studies (Ngeleka et al., 2003; Vu-Khac find more et al., 2007). Both paa and eae play a role in attaching/effacing (AE) adhesion in enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) (Nataro & Kaper, 1998; Batisson et al., 2003). In pig EPEC O45 strains, paa is associated with the presence of eae and the AE phenotype in vivo and in vitro (An et al., 1999). In agreement, all paa-positive isolates were eae-positive in this study, although the prevalence of paa was somewhat lower.

The relationships of EAST1 with faeG, STa, STb, AIDA-I, and combinations of VGs are easily explained by the clustering of STa, STb, EAST1, and faeG on the pTENT2 plasmid of porcine ETEC from Ontario (Leclerc et al., 2007). These findings suggest that E. coli strains from diseased swine possess a variety of VGs associated with various pathogenic E. coli, such as ETEC, EHEC, STEC, and EPEC. Among all Lepirudin ETEC strains, VGs astA, STa, Stx2e, and F4 were the most frequent, while the prevalence of STb, paa, sepA, and AIDA-I appeared to be lower than has been reported previously from ETEC isolates (Boerlin et al., 2005; Zhang et al., 2007). Resistance to antimicrobials in pathogens is an increasing threat to animal and human health. Compared with their susceptible counterparts, resistant bacterial infections are generally associated with increased morbidity, mortality, and treatment expense (Barza, 2002; Barza & Travers, 2002; Travers & Barza, 2002). Other investigators have also reported more frequent resistance, physical linkages, and statistical associations between resistance and VGs in swine pathogenic E. coli (Boerlin et al., 2005; Travis et al., 2006). In this study, E.