Pathogenic bacteria in Finnish bulk tank milk

Area of Science:

• Food Safety
• Microbiology
• Veterinary Public Health

Background:

• Finnish raw cow milk has high hygienic standards, with low overall bacterial counts.
• However, the prevalence of specific pathogenic bacteria in raw milk remains underreported.
• Understanding pathogen presence is crucial for public health risk assessment.

Purpose of the Study:

• To determine the occurrence of key pathogenic bacteria in raw cow milk from Finnish bulk tanks.
• To assess the hygienic quality of milk by measuring total bacterial and E. coli counts.
• To investigate potential correlations between general hygiene indicators and pathogen presence.

Main Methods:

• Collected raw cow milk samples from bulk tanks at 183 Finnish farms.
• Tested for Listeria monocytogenes, Campylobacter spp., Salmonella spp., STEC, coagulase-positive staphylococci, Yersinia spp., and Bacillus cereus group.
• Quantified total bacterial counts and E. coli levels as hygiene indicators.

Main Results:

• Listeria monocytogenes detected in 5.5% of samples; STEC (stx2) in 2.7%; Yersinia enterocolitica (non-pathogenic strains) in 7.7%.
• Coagulase-positive staphylococci found in 34.4% and Bacillus cereus group in 20.8% of samples.
• No Campylobacter or Salmonella detected; no correlation found between hygiene indicators and pathogen presence.

Conclusions:

• Pathogenic bacteria can be present in raw milk even on farms with excellent production hygiene.
• The low concentrations found do not negate the risk, as some pathogens can grow during refrigeration.
• Consumption of raw milk and related products poses a potential risk for food poisoning due to low infectious doses.