A survey of Salmonella, Escherichia coli and antimicrobial resistance in frozen, part-cooked, breaded or battered chicken products on retail sale in the United Kingdom.

Abstract

Frozen, breaded chicken products have been implicated in Salmonella outbreaks, and may be incorrectly perceived as ready-to-eat, leading to mishandling or undercooking by consumers. This study aimed to assess the prevalence of Salmonella and antimicrobial resistant (AMR) E. coli in these products. Samples of frozen, raw or partly cooked, coated chicken products were collected between April and July 2021 from retailers in the UK and tested for Salmonella spp., generic Escherichia coli, extended spectrum beta-lactamase-producing, colistin-resistant and carbapenem-resistant E. coli. One isolate of each bacterial type from each sample was selected for minimum inhibitory concentration determination for a range of antimicrobials. Salmonella was detected in 5 of 310 (1.6%) samples, identified as Salmonella Infantis in three samples and S. Java in two. One S. Infantis isolate was multi-drug resistant, while the other Salmonella isolates were each resistant to at least one class of antimicrobials. Generic E. coli were detected in 113 samples (36.4%), with multi-drug resistance being demonstrated in 20.0% of these. E. coli with the ESBL phenotype were detected in 15 (4.8%) of samples and the AmpC phenotype in 2 (0.6%). A colistin resistant E. coli was isolated from one sample; this possessed the mcr-1 gene. No carbapenem-resistant E. coli were detected. The five Salmonella-positive samples from this study, together with 20 Salmonella-positive products from an earlier study in 2020/2021, were cooked according to the manufacturers' instructions. Following cooking, Salmonella was not detected in any samples. This survey demonstrates continued contamination of frozen, coated chicken products with Salmonella, and provides data on the prevalence of AMR in these products.