Assessment of the Microbiological Quality and Safety of Unpasteurized Milk Cheese for Sale in England between 2019 and 2020

Cheese made with unpasteurized milk has been associated with outbreaks of illness. However, there are limited data on the prevalence of Shiga toxin-producing Escherichia coli (STEC) in these products and a lack of clarity over the significance of E. coli as a general indicator of hygiene in raw milk cheeses. The aim of this study was to provide further data to address both of these issues, as well as assessing the overall microbiological quality of raw milk cheeses available to consumers in England. A total of 629 samples of cheese were collected from retailers, catering premises, and manufacturers throughout England. The majority (80%) were made using cow's milk, with 14% made from sheep's milk and 5% from goat's milk. Samples were from 18 different countries of origin, with the majority originating from either the United Kingdom (40%) or France (35%). When interpreted against European Union microbiological criteria and United Kingdom guidance, 82% were considered to be of satisfactory microbiological quality, 5% were borderline, and 12% were unsatisfactory. Four samples (0.6%) were potentially injurious to health due to the isolation of STEC from one, >10(4) CFU/g of coagulase-positive staphylococci in two, and >100 CFU/g of Listeria monocytogenes in the fourth sample. Indicator E. coli and Listeria species were detected more frequently in soft compared with hard cheese. Higher levels of indicator E. coli were significantly associated with a greater likelihood of detecting Shiga toxin genes (stx(1) and/or stx(2)).

Automated summary

Cheese made with unpasteurized milk has been associated with outbreaks of illness. This study aimed to provide further data on the prevalence of Shiga toxin-producing Escherichia coli (STEC) in these products and assess the microbiological quality of raw milk cheeses available in England. The results showed that 82% of the cheese samples were considered to be of satisfactory microbiological quality, while 5% were borderline and 12% were unsatisfactory. A small percentage of samples were potentially injurious to health due to the presence of STEC, coagulase-positive staphylococci, and Listeria monocytogenes.