Monitoring of foodborne pathogenic bacteria in vending machine raw milk in Piedmont, Italy

Raw milk consumption in Italy has increased over the past three years following the enactment of a national law that allows the sale of unpacked and unpasteurized cows' milk via vending machines on the farm and at markets. From 2009 to 2011, a three-part monitoring survey of raw milk sold though vending machines was carried out to investigate for the occurrence of Salmonella spp., Escherichia coli O:157, Campylobacter spp. and Listeria monocytogenes. A total of 618 raw milk samples were collected from 112 dairy herds supplying 131 raw milk vending machines. Of the samples tested, 0.3% were positive for Salmonella spp., 0.2% for E. coli O:157, 1.5% for Campylobacter spp., and 1.6% for Listeria monocytogens. Multivariate analysis showed no effect of seasonality, average daily temperature, herd size, sample collection point or distance between herd and vending machine; however, there was a statistically significant correlation between a previous finding of pathogens and recurrence of contamination. The monitoring survey results confirm that unpasteurized milk can be a vehicle of a variety of microorganisms and an important source of foodborne illness outbreaks.