Characteristics of ciprofloxacin and cephalosporin resistant Escherichia coli isolated from turkeys in Great Britain

1. A field study was performed to investigate the presence and characteristics of ciprofloxacin-resistant, extended spectrum -lactamase (ESBL) and AmpC Escherichia coli from turkeys in Great Britain. E. coli were isolated from approximate to 9000 boot swab samples from 27 different farms owned by four different companies. Between 1 and 14 visits were made to each farm (mean 3) at between 0 and 15m intervals (mean approximate to 5m). 2. CHROMagar ECC with and without ciprofloxacin or cephalosporin antibiotics was used as selective isolation media. Representative isolates with different phenotypes were tested for mutations in gyrA and for: qnrA, B, S, qepA and aac(6)-Ib genes, for ESBL phenotype, the presence of bla CTX-M genes and plasmid type, and for ampC genes. Representative ciprofloxacin-resistant and CTX-M isolates were further tested for serotype and PFGE type. On ciprofloxacin selective media 55% of samples yielded ciprofloxacin resistant E. coli and of those further analysed, most had ciprofloxacin MICs >4 mg/l and mutations in gyrA. 3. For the different companies, the mean number of samples per farm with cefoxitin- or cefotaxime-resistant isolates ranged from 1 center dot 0% to 61 center dot 9% and 4 center dot 7% to 31 center dot 7% respectively. Cefotaxime-resistance was most commonly associated with an ESBL phenotype, a CTX-M-1 or CTX-M-14 sequence type and an I1- or K plasmid inc type. The mechanism of cefoxitin resistance was not determined for most isolates, but where determined it was bla CMY-2. 4. PFGE and serotyping showed clonally-related isolates persisting over multiple visits suggesting both more prudent use of antibiotics and improved farm hygiene are needed to address the issue of antimicrobial resistance in isolates from turkeys.