A survey of food-borne and antimicrobial resistance-harbouring bacteria in meat by-products from knackeries and associated equipment and kennels

BACKGROUND: In Ireland, meat by-products (MBP) harvested at knackeries from farmed animals that have not died of an infectious or systemic disease are legally permitted to be fed to dogs in kennels and packs of hounds. There is limited information available on the risks of spreading foodborne bacteria or antimicrobial resistant (AMR) determinants to dogs, their handlers or the associated environment. The aim of this study was to investigate the distribution of Salmonella serovars, Listeria monocytogenes, Campylobacter species, enterococci, their associated AMR determinants and the level of Escherichia coli in samples of MBP from knackeries and associated equipment and kennels. For this purpose, 313 fresh and 208 frozen MBP samples from 22 knackeries, 16 swabs of mincing equipment from two of the knackeries and 138 swabs from kennels adjacent to seven of the knackeries were collected and processed over a 12-month period. RESULTS: From the 521 MBP samples analysed, a total of 77 Salmonella (14.8%), 101 L. monocytogenes (19.4%), 12 Campylobacter (2.3%), 271 Enterococcus faecalis (52.0%) and 127 Enterococcus faecium (24.4%) strains were recovered. The 154 analysed environmental samples from kennels and mincing equipment yielded 194 isolates (3 Salmonella, 85 E. coli, 76 E. faecalis and 30 E. faecium.). E. coli was quantifiable in 423 of the 521 MBP samples with log counts per gram ranging between 1 and 6. AMR characterisation of 168 E. coli, enterococci and Salmonella isolates from MBP and environmental samples showed high levels of AMR including multi-drug resistance (MDR) with 63.6%, 9.1%, 29% and 45.8% of E. coli, Salmonella, E. faecalis and E. faecium isolates, respectively showing resistance to three or more antimicrobials (MDR) CONCLUSIONS: The findings of this survey confirm that MBP from fallen animals contain high levels of zoonotic and AMR-harbouring bacteria that pose a risk of transmission to dogs, their handlers, and the environment.