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Objectives To detect and characterize Escherichia coli strains and pCT-like plasmids implicated in the dissemination of the CTX-M-14 gene in animals and humans, in England and Wales. Methods UK CTX-M-14-producing E. coli (n = 70) from cattle (n = 33), turkeys (n = 9), sheep (n = 2) and humans (n = 26) were screened using multiplex PCR for the detection of a previously characterized plasmid, pCT. Isolates found to be carrying two or more pCT genetic markers were further analysed using PFGE. Their antimicrobial-resistance genes and virulence genes were also determined. These plasmids were transferred to Salmonella enterica serotype Typhimurium 26R and further examined for incompatibility type, genetic environment of the blaCTX-M-14 gene, size, restriction fragment length polymorphism (RFLP) and nikB sequence. Results The 25 E. coli isolates carrying pCT genetic markers generated 19 different PFGE profiles, and 23 isolates had different virulence and antimicrobial-resistance gene patterns. One isolate from cattle was a verotoxigenic E. coli (‘VTEC’); the rest were commensal or extra-intestinal pathogenic E. coli. pCT-like plasmids with similar molecular characteristics (size, replicon type, RFLP pattern, pCT markers and genetic environment of the blaCTX-M-14 gene) were detected in 21/25 of the field isolates, which comprised those from cattle (n = 9), turkeys (n = 8) and humans (n = 4). All pCT-like plasmids were conjugative, and most were IncK (n = 21) and had the same local genetic environment flanking the blaCTX-M-14 gene (n = 23). RFLP analysis demonstrated ≥75% similarity among most plasmids (n = 22). Conclusions pCT-like plasmids were common vectors for horizontal dissemination of 30% of the blaCTX-M-14 genes to different E. coli isolates from humans, cattle and turkeys. [ABSTRACT FROM PUBLISHER]

This study investigated the potential spread of CTX-M-14 Escherichia coli from a known ESBL E. coli positive farm and risk factors for the presence of CTX-M E. coli on dairy farms. Between November 2009 and March 2010, 65 farms in North West England and North Wales were visited and animals sampled for E. coli producing CTX-M ESBLs. Seventeen of these were known to have received animals from a known ESBL E. coli positive 'index' farm since 2005 (linked farms). The prevalence of CTX-M E. coli in the population of linked farms was 58.8% (10/17; CI(95%) 32.9-81.6%) and in the randomly selected control population was 35.4% (17/48; CI(95%) 22.2-50.5%). There was no significant (p>0.05) linkage for the detection of any CTX-M E. coli or specifically a CTX-M-14 E. coli to the index farm. Group 1 (CTX-M-15, CTX-M-55, CTX-M-1, CTX-M-32), group 2 (CTX-M-2) and group 9 (CTX-M-14, CTX-M-14 B, CTX-M-27) CTX-M E. coli were identified on the study farms. Molecular analysis revealed that three plasmids from linked farms had similar sizes (95 kbp), replicon type (IncK) and backbone genes as that from the index farm. Logistic regression analysis revealed that farms that had used a 3rd or 4th generation cephalosporin (ceftiofur, cefoperazone and cefquinome) in livestock in the last 12 months were nearly 4 times more likely to have ESBL E. coli present (p=0.037; OR=3.93). There was no significant association between presence of CTX-M E. coli and the use of any 1st or 2nd generation cephalosporins. Several other risk factors for the presence of CTX-M E. coli were identified, such as storage of slurry in a pit, operating an open herd policy and infrequent cleaning of calf feeding equipment., (Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.)