Pathogens in raw milk, Salmonella and Listeria monocytogenes were discussed at the annual meeting of a European microbial risk assessment network.

A total of 25 European unio countries as well as Switzerland and Norway are members of the network. The next meeting is in May 2020 in Parma.

Results from studies on raw milk quality from vending machines in Switzerland, Germany and Austria were presented. The Scientific Network on Microbiological Risk Assessment held its annual meeting in May 2019 in Parma.

Raw milk studies and findings
The German research involved 159 samples of raw cow milk from farm-gate vending machines collected between 2016 and 2018. Two samples were positive for Campylobacter, seven for Shiga toxin-producing E. coli (STEC), and six for Listeria monocytogenes.

The study in Austria included 74 samples of raw cow milk collected in July and August 2017. Twenty-two samples exceeded limits for total viable count (TVC) considering the Austrian national regulation for raw milk states the limit is 50,000 CFU/mL. Salmonella Dublin and Campylobacter jejuni were detected once and VTEC was isolated in two samples.

A Swiss study looked at microbiological quality of 73 samples of raw cow’s milk sold directly from farms to consumers. E. coli and coagulase-positive Staphylococci were each detected in 30.1 percent of samples. TVC results for raw milk from vending machines were higher than those from pre-filled bottles, showing the importance of correct cleaning and disinfection of vending machines.

Swedish officials presented a study on Campylobacter spp., Salmonella spp. and STEC in milk filters from dairy farms. A total of 302 milk tank filters were collected from three regions in Southern Sweden, each from a different farm that provided the filter after morning milking.

Forty-five isolates from 42 STEC-positive samples were investigated by WGS for virulence factors such as stx1, stx2 and eae. Serotyping on 29 isolates found the most common serotype was O145:H28. Two isolates belonged to O26:H11 and one to O157:H7. only the latter was of high pathogenicity.

Thirty-eight samples were positive for Campylobacter of which 34 were jejuni and four were lari. Pathogen occurrence was higher in farms with more than 50 cows and an untethered milking system.

Microbial meat results
Results from the project Safemeat were presented by Belgian officials. A total of 105 pig carcasses were sampled and 64 percent were positive for Salmonella spp. Microbiological analysis showed the number of positives from rectum and mouth swabs increased after the dehairing process.

Research investigating the contamination rate and sources of Listeria monocytogenes in carcasses in Flemish slaughterhouses was also presented.

Listeria was isolated in three slaughterhouses and 42 of 90 carcasses were positive, from different areas of the carcass. To map contamination routes, samples from hides and carcasses from four slaughterhouses were collected showing 97 percent and 47 percent positive, respectively. This means direct transfer from hides to carcasses and persistent strains in the environment are important sources of contamination at the abattoir.

Croatia presented research on quality and microbiological safety of portioned raw meat on the last day of the expiry date. A total of 150 pre-portioned raw meat and 150 ground meat samples from different species were collected.

Salmonella spp. was detected in 10 samples and 22 poultry meat samples had Enterobacteriaceae concentration of more than 105 CFU/g. This indicates it is not possible to extend shelf life of these products.

Hepatitis E, Listeria growth and AMR in shellfish
Pork liver sausages and raw meat sausages from the Swiss retail market were tested for Hepatitis E virus (HEV). RNA of the virus was detected in 18 samples: 11 of 42 for liver sausages and seven of 190 for raw meat sausages.

Food businesses should apply strategies to minimize risks such as heat treatment of products and control of raw meat while consumers who want to minimize the risk of HEV infection should avoid eating raw meat products, especially those containing raw liver.

Ireland’s delegate covered foods that do not support the growth of Listeria monocytogenes. Fresh, uncut and unprocessed vegetables and fruits are legally considered unable to support growth of Listeria but evidence of survival and growth on whole fresh produce has been shown in some studies. It was agreed a questionnaire from Ireland would ask network members for their views and experiences on the topic.

Denmark shared research on the risk of introducing antimicrobial resistance (AMR) via shellfish and pangasius from Asia. Pangasius is imported as fillet for further cooking while prawns are brought in as raw and pre-cooked and the latter are often ready to eat.

There were 300 frozen samples collected. All pangasius fillets samples were contaminated with Enterococci and 52 percent with E. coli. While 89.7 percent of prawns samples had Enterococci and 25 percent E. coli. Ten multidrug resistant E. coli were isolated.

Most resistance genes in the study are already present in Danish products but mobile quinolones resistance genes were also identified. One isolate showed resistance to ESBL, macrolide, colistin and mobile fluoroquinolone resistance. The products may pose a risk to consumers by introducing AMR genes still rare in domestic food sources.