Occurrence of foodborne pathogens in Italian soft artisanal cheeses displaying different intra- and inter-batch variability of physicochemical and microbiological parameters

Abstract

Artisanal cheeses are produced in small-scale production plants, where the lack of full automation and control of environmental and processing parameters suggests a potential risk of microbial contamination. The aim of this study was to perform a longitudinal survey in an Italian artisanal factory producing a spreadable soft cheese with no rind to evaluate the inter- and intra-batch variability of physicochemical and microbial parameters on a total of 720 environmental and cheese samples. Specifically on cheese samples, the evaluation was additionally performed on physicochemical parameters. Cheese samples were additionally collected during 15 days of storage at constant temperatures of 2 and 8°C, as well as a dynamic profile of 2°C for 5 days and 8°C for 10 days. Furthermore, Enterobacteriaceae isolates were identified at species level to have a better knowledge of the environmental and cheese microbiota potentially harboring human pathogens. High inter-batch variability was observed for lactic acid bacteria (LAB) and total bacteria count (TBC) in cheese at the end of production but not for pH and water activity. A temperature of 8°C was associated with a significantly higher load of Enterobacteriaceae in cheeses belonging to batch 6 at the end of storage, and this temperature also corresponded with the highest increase in LAB and TBC loads over cheese shelf life. Results from generalized linear mixed models (GLMMs) indicated that drains in the warm room and the packaging area were associated with higher levels of TBC and Enterobacteriaceae in cheese. Regarding foodborne pathogens, no sample was positive for verotoxigenic Escherichia coli (VTEC) or Listeria monocytogenes, whereas six Staphylococcus aureus and one Salmonella pullorum isolates were collected in cheese samples during storage and processing, respectively. Regarding Enterobacteriaceae, 166 isolates were identified at species level from all batches, with most isolates belonging to Klebsiella oxytoca and pneumoniae, Enterobacter cloacae, Hafnia alvei, and Citrobacter freundii evidencing the need to focus on standardizing the microbial quality of cow milk and on hygienic procedures for cleaning and disinfection especially in warm and maturation rooms. Further studies should be performed to investigate the potential pathogenicity and antimicrobial resistance of the identified Enterobacteriaceae species in artisanal cheeses.

Occurrence and genomic characterization of antimicrobial-resistant and potential pathogenic <i>Escherichia coli</i> from Italian artisanal food productions of animal origin

“…The dairy and pork meat-based artisanal products tested were represented by a soft cheese made of pasteurized cow milk, added by salt, calf rennet, and starter cultures, and a 6-month ripened fermented dried sausage, commonly named “salami”, from an Italian swine autochthonous breed with no addition of starter cultures or nitrites/nitrates. Sampling was performed as previously described (Pasquali et al ., 2022 ; Pasquali et al ., 2023 ). Briefly, 6 batches of each production were sampled at the 2 artisanal facilities, located in Northern Italy, between January 2020 and May 2021, by collecting raw materials (cheese: raw and pasteurized milk, calf rennet; salami: minced meat mixture), intermediate products (cheese: cheese stored within warm and maturation room; salami: salami stored for 1 week inside drying area as well as for 3, 10 and 18 weeks inside ripening area), final products (cheese: cheese packed on day 0 of production along with stored cheese at day 4, 8, 11 and 15 at 2°C, 8°C and 2°C for 5 days followed by 8°C for 10 days; salami: 28 weeks ripened salami), and environmental swabs from processing areas (cheese: wall, manhole and gloves of workers inside warm, maturation and packaging area; salami: wall, manhole, processing surfaces and filler stuffer machine inside stuffing, drying and ripening area).…”

Resistome and virulome diversity of foodborne pathogens isolated from artisanal food production chain of animal origin in the Mediterranean region

“…Isolates were collected as previously described (Pasquali et al ., 2022 ). Briefly, the sampling took place in four different Mediterranean countries: Italy, Portugal, Spain and Morocco.…”

“…2,800 samples. ISO standard methods as well as PCR and biochemical tests were applied for the isolation and identification of L. monocytogenes , Salmonella enterica and S. aureus as previously described (Pasquali et al ., 2022 ). Retrieved bacterial pathogens are reported in Table 1 .…”

“…Within the H2020 PRIMA European funded project ARTISANEFOOD ( http://www.ipb.pt/artisanefood/ ), partners from Portugal, Spain, Italy, and Morocco identified local, artisanal fermented food products of dairy and meat origins. In order to gain a snapshot of the sanitary and hygienic status of these productions, samples were collected from raw materials, intermediate and finished products as well as the environment (Pasquali et al ., 2022 ). Since few data on antimicrobial resistance and virulence properties of isolates from artisanal productions are available (Graham et al ., 2017 ) forty-three isolates collected in the ARTISANEFOOD project belonging to L. monocytogenes , Salmonella enterica and S. aureus were investigated for their resistome and virulome, in order to elucidate their diversity and potential dissemination within small-scale production industries.…”

Microbial Evolution in Artisanal Pecorino-like Cheeses Produced from Two Farms Managing Two Different Breeds of Sheep (Comisana and Lacaune)

“…Although the organoleptic quality of artisanal cheeses produced using raw milk and natural curd is superior to that of the most widespread pasteurized milk cheese, these products may pose a threat to consumers’ health, and therefore, their safety should be carefully assessed to protect the producer and consumer interests [ 17 , 18 ]. Thus, monitoring microbiota composition and its evolution during fermentation and ripening is crucial for obtaining products with optimal sensory properties and safety characteristics [ 19 ].…”