Antibiotic Resistant Escherichia coli in Uncooked Meat Purchased from Large Chain Grocery Stores and in Raw Dog Food Purchased From Pet Stores in the Same City.

Although previous studies have associated feeding dogs uncooked meat with their carriage and excretion of antibiotic resistant (ABR) Escherichia coli, this practice remains popular amongst dog owners in some countries, including the UK. Uncooked meat fed to dogs is purchased from stores selling meat primarily for human consumption, or it is a brand of commercial raw dog food (RDF), which is commonly sold frozen and thawed prior to feeding. We tested 58 packets of uncooked meat (beef, chicken, lamb and pork) purchased from large chain grocery stores (15 stores) and 15 packets of thawed, chicken-based RDF (11 brands) for the presence of ABR E. coli. All samples were purchased from the city of Bristol, UK. Among grocery store-purchased meat, chicken samples were significantly more likely to be positive for E. coli resistant to amoxicillin, spectinomycin, streptomycin, and the critically important antibiotics cefotaxime and ciprofloxacin, than other types of meat. When comparing grocery store chicken to chicken-based RDF we found no significant difference in sample-level positivity for resistant E. coli, which, for RDF was 80% (amoxicillin), 80% (spectinomycin), 87% (streptomycin), 27% (amoxicillin-clavulanate), 27% (cefotaxime) and 47% (ciprofloxacin). We conclude that despite it having been purchased frozen and thawed prior to testing according to the manufacturer's instructions, contamination of RDF with ABR E. coli is similar to that of uncooked meat primarily intended for human consumption after cooking, and so the same strict hygiene practices are advised when handling RDF as uncooked meat. Our findings provide a rationale to explain why feeding uncooked meat or RDF to dogs in the city of Bristol is associated with them excreting E. coli resistant to critically important antibiotics. ### Competing Interest Statement M.B.A. is married to the owner of a veterinary practice that sells various mass-manufactured dog foods amounting to a value less than 5% of total turnover. Otherwise, the authors declare no competing interests.