A Cross-Sectional Survey of Foodborne Pathogens in Farm-Sold Frozen Dessert in Switzerland.

Abstract

Reports in the literature indicate that ice cream has been associated with illnesses linked to several pathogens, including Listeria monocytogenes. Farm-produced ice cream and sorbet are commonly marketed in Switzerland, yet data on their bacteriological quality are scarce. This study assessed the prevalence of foodborne pathogens and hygiene indicator organisms in frozen dessert (ice cream and sorbet) produced and marketed by Swiss farms. Between June and September 2025, 100 samples (ice cream, n = 61; sorbet, n = 39) were collected from 48 farms across 10 cantons. Samples were analyzed qualitatively for Salmonella, Shiga toxin-producing Escherichia coli (STEC), and Listeria spp., and quantitatively for E. coli, Staphylococcus aureus, and members of the Bacillus cereus group. Neither Salmonella, STEC, nor L. monocytogenes were detected. Escherichia coli and S. aureus counts remained below 1 log CFU/g and 2 log CFU/g, respectively. Members of the B. cereus group (B. mosaicus subsp. cereus, B. mosaicus, B. mycoides, B. cereus s.s., B. toyonensis) were identified in 15% of samples, at levels ranging from 2.00 to 3.57 log CFU/g. One isolate of Bacillus mosaicus subsp. cereus harboring the cereulide synthetase gene cluster was recovered from an almond ice cream sample (2 log CFU/g). The findings indicate an overall absence of major bacterial pathogens and low levels of indicator organisms in Swiss farm ice cream and sorbet but highlight the relevance of B. cereus group members as potential hazards requiring monitoring.