Scottish survey finds low contamination in ground beef

A survey on ground beef in Scotland has found low levels of Campylobacter, Salmonella and Shiga toxin-producing E. coli (STEC).

The work, funded by Food Standards Scotland, was done in 2019 with 1,009 samples of fresh ground beef, also known as minced beef, on retail sale across the country. For 33 samples country of origin was unknown. Of the rest, all except three were labeled as coming from the UK and Ireland.

It looked at the frequency of Campylobacter, Salmonella and STEC findings, and two process hygiene indicator organisms: counts of generic E. coli and Aerobic Colony Count (ACC). Levels of antimicrobial resistance in detected pathogens and generic E. coli were also assessed.

Only one sample was positive for Campylobacter and Salmonella was detected three times; Salmonella Mbandaka twice and Salmonella Dublin once.

E. coli results
In total, 35 samples were confirmed as STEC positive and only three were E. coli O157:H7. Overall, 226 presumptive samples were identified but this is not the same as finding viable STEC bacteria, according to the report.

Twenty two different serotypes featured among the 35 STEC isolates. With four each, E. coli O113:H4 and E. coli O84:H20 were the most common.

Two of the O157:H7 STEC study isolates were similar to three Scottish clinical strains from a UK outbreak of E. coli O157 phage type (PT) 21/28. Mince isolates matched clinical ones. An outbreak investigation concluded the source of infection was most likely Scottish cattle.

The study found no significant differences between confirmed STEC and all factors such as season, geographical location, or retailer type.

Most samples had levels of generic E. coli below the limit of detection. ACC was above the limit of detection in most tests.

The majority of isolates were susceptible to all the antibiotics they were tested against. Evidence for AMR was identified in 12 of 151 isolates tested. No isolates were resistant to any critically important antimicrobials.

Assessing scale of problem
Ground beef sold in Scotland is not intended to be eaten raw or less than thoroughly cooked, also known as rare.

Dr. Marianne James, head of risk assessment at Food Standards Scotland, said the levels of microbiological quality were encouraging, and in line with past studies in other countries.

“The levels of AMR in beef mince were low, and any resistance found was to commonly used, first line antibiotics. This provides some reassurance that fresh beef mince on retail sale in Scotland is unlikely to currently be a major foodborne route for transmission from cattle to humans of AMR to critically important antimicrobials. Against that background, adherence to cooking instructions on all beef mince packaging and strict hygiene when handling raw mince, remains important to avoid any potential illness associated with the product,” she said.

FSS worked with Scotland’s Rural College on the project and George Gunn, head of Veterinary Epidemiology at SRUC, said: “Our survey provided a baseline understanding of the microbiological status of fresh minced beef on retail sale in Scotland while also identifying gaps in our knowledge and the evidence base.”

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