Food-Borne Pathogens and Contaminants in Raw Milk – A Review

The aim of the present review is to highlight the threats to human health posed by consumption of milk and dairy products. The interest in drinking raw milk has been growing in some societies as many people believe it has health benefits. Raw milk is promoted as ‘health food’ despite the fact that it poses a realistic microbiological hazard for the consumers’ health or life. Food-borne disease outbreaks associated with Campylobacter spp., Salmonella spp., shigatoxin-producing Escherichia coli, Brucella melitensis, Mycobacterium bovis and tick-borne encephalitis virus have been traced to the consumption of raw milk, however, many other microorganisms that can be present in milk are considered as potential food-borne pathogens to humans. The other common causative agents in food-borne disease outbreaks are bacterial toxins produced by Bacillus, Clostridium and Staphylococcus spp. Some of the milk pathogens harbour antimicrobial resistant genes, which can be transferred to commensal bacteria. Most dangerous are methicillin-resistant Staphylococcus aureus and extended spectrum beta lactamase/AmpC gene-carrying bacteria from the family of Enterobacteriaceae, which might negatively affect the treatment of infections in humans. Fungi are not considered as food-borne pathogens for humans, however their secondary metabolites, mycotoxins, constitute a potential threat to public health. Mycotoxins or their metabolites detected so far in milk samples include aflatoxins, ochratoxin A, zearalenone and its metabolites, fumonisins, de-epoxy-deoxynivalenol and cyclopiazonic acid.