Foodborne Pathogens in In-Line Milk Filters and Associated On-Farm Risk Factors in Dairy Farms Authorized To Produce and Sell Raw Milk in Northern Italy

Abstract

<jats:p>All dairy farms authorized to produce and sell raw milk in a province of Northern Italy were investigated to determine the presence of Campylobacter spp., verocytotoxin-producing Escherichia coli (VTEC), Listeria monocytogenes, and Salmonella spp. in in-line milk filters and to assess their association with suspected risk factors on farms. A logistic regression model was used to analyze data collected describing the characteristics and management practices of 27 farms and the microbiological status of 378 in-line milk filters by both culture-based and molecular methods. Thermotolerant Campylobacter, VTEC, and L. monocytogenes were detected in 24 (6.45%), 32 (8.4%), and 2 (0.5%) samples, respectively. No Salmonella spp. were detected. For risk analysis, data of L. monocytogenes and Salmonella spp. were not included in the model because of the low prevalence or absence of these organisms. The univariate analysis disclosed that the presence of VTEC and/or Campylobacter spp. in milk filters was associated with lack of cleanliness of bedding, water trough, and feed trough; nonevaluation of water hardness; lack of cleanliness of milk tank; and nonapplication of forestripping. After multivariate analysis, an association was observed with inadequate cleanliness of bedding and milk tank and the nonapplication of forestripping. PCR analysis of milk filters was a rapid and sensitive method for the microbiological evaluation of herd contamination status and should be included among the registration requirements for the authorization to produce and sell raw milk. Specific control actions must be incorporated into the farmer's daily practices to ensure the low-risk production of raw milk.</jats:p>

Prevalence in Bulk Tank Milk and Epidemiology of Campylobacter jejuni in Dairy Herds in Northern Italy

“…Stanley and Jones (21) described an incidence between 3.8 and 8.1% in the United Kingdom and Yang et al (22) recovered C. jejuni from 27.3% of the bulk tank milk in China. The prevalence reported here is in line with a study conducted in an area close to that considered in our survey, in which C. jejuni was detected in 14.8% (4/27) of the bulk milk filters from farms authorized to produce and sell raw milk (6). However, the isolation rate observed here was higher than that reported in the same period during official controls of raw milk at vending machines in Lombardy (Ͻ0.6%) (http://www.sanita .regione.lombardia.it).…”

“…The presence of C. jejuni in milk can also be due to direct contact with contaminated sources in the dairy farm environment and some studies identified wild birds as a possible reservoir for Campylobacter transmission to livestock (6,13).…”

“…Wild birds may also play a role in spreading the microorganism within the environment and to livestock (13). In an area close to that considered in our survey, Giacometti et al (6) associated the presence of pests (mainly birds) in the herd with the detection of Campylobacter spp. in milk filters.…”

“…In Italy, contamination of milk by C. jejuni has assumed more importance since 2004, when the sale of raw milk for human consumption by self-service automatic vending machines began and some outbreaks were reported following raw milk consumption: two in the Emilia Romagna Region in 2008 and 2009, one in the Veneto Region and another in the Marche Region (6). In 2011, the Italian Ministry of Health reported a national prevalence of 2.3% for thermotolerant Campylobacter spp.…”

Scientific Opinion on the public health risks related to the consumption of raw drinking milk

“…Other factors (sampling site, vending machine site, average daily temperature, herd size, season) were not associated with the presence of pathogens. Other surveys have reported the isolation of pathogens from raw milk sold through vending machines (Giacometti et al, 2012b;Serraino et al, 2013;Gasperetti et al, 2014). Tremonte et al (2014) analysed 30 samples collected from vending machines in southern Italy for indicator microorganisms.…”