Four-Year Monitoring of Foodborne Pathogens in Raw Milk Sold by Vending Machines in Italy

Abstract

Prevalence data were collected from official microbiological records monitoring four selected foodborne pathogens (Salmonella, Listeria monocytogenes, Escherichia coli O157:H7, and Campylobacter jejuni) in raw milk sold by self-service vending machines in seven Italian regions (60,907 samples from 1,239 vending machines) from 2008 to 2011. Data from samples analyzed by both culture-based and real-time PCR methods were collected in one region. One hundred raw milk consumers in four regions were interviewed while purchasing raw milk from vending machines. One hundred seventy-eight of 60,907 samples were positive for one of the four foodborne pathogens investigated: 18 samples were positive for Salmonella, 83 for L. monocytogenes, 24 for E. coli O157:H7, and 53 for C. jejuni in the seven regions investigated. No significant differences in prevalence were found among regions, but a significant increase in C. jejuni prevalence was observed over the years of the study. A comparison of the two analysis methods revealed that real-time PCR was 2.71 to 9.40 times more sensitive than the culture-based method. Data on consumer habits revealed that some behaviors may enhance the risk of infection linked to raw milk consumption: 37% of consumers did not boil milk before consumption, 93% never used an insulated bag to transport raw milk home, and raw milk was consumed by children younger than 5 years of age. These results emphasize that end-product controls alone are not sufficient to guarantee an adequate level of consumer protection. The beta distribution of positive samples in this study and the data on raw milk consumer habits will be useful for the development of a national quantitative risk assessment of Salmonella, L. monocytogenes, E. coli O157, and C. jejuni infection associated with raw milk consumption.

Human campylobacteriosis related to the consumption of raw milk sold by vending machines in Italy: Quantitative risk assessment based on official controls over four years

“…C. jejuni were detected in 53 out of 15,282 (0.34%) raw milk samples. No significant differences were shown in the prevalence among regions by multivariate analysis (Giacometti et al, 2013). Four farms located in three different regions resulted positive twice in two successive months but no seasonality in the prevalence of positive samples was shown.…”

“…Official microbiological records of raw milk samples from selfservice vending machines in seven Italian regions monitored by the regional Veterinary Authorities from 2008 to 2011 were collated from a previous survey and used for this RA model (Giacometti et al, 2013). Briefly, the seven regions, Emilia Romagna, Lazio and Tuscany (pooled data), Lombardy, Marche, Piedmont, Sicily and Veneto, account for 1236 vending machines, i.e., 89.43% of the 1382 vending machines registered in Italy, providing a high proportion of the true national scenario (Italian Ministry of Health, 2011).…”

“…All samples taken in single for each vending machine for official controls from 2008 to 2011 were considered in the study (Giacometti et al, 2013). A total of 15,282 samples were analysed for C. jejuni using the official International Organization for Standardization (ISO) cultural methods, ISO 10272-1:2006.…”

“…To take into account the qualitative results obtained during the official control survey (Giacometti et al, 2013) and lacking quantitative data, the raw milk concentration of C. jejuni was modelled considering the detection limit of the microbiological method applied (usually considered 0.04 CFU, −1.398 log CFU/ml) as follows: given the ( ) of the Normal distribution for the concentration of the pathogen in milk, the equation was resolved for ( ) obtaining a fraction of modelled raw milk samples above the detection limit comparable to the prevalence observed during the official control survey.…”

“…In Italy, the results of diagnostic activities performed in different surveys and official control data showed that the prevalence of C. jejuni in raw milk samples collected by self-service vending machines varies from 0 to 1.5% (Giacometti et al, 2012b;Bianchi et al, 2013;Giacometti et al, 2013). In addition, two outbreaks of C. jejuni linked to the consumption of raw milk have been reported in Italy, one in the Veneto region and the other in the Marche region (Amato et al, 2007;Tonucci, 2011 personal communication).…”