Salmonellae, Salmonellosis, and Dairy Foods: A Review

Abstract

Salmonellae continue to be a major concern for the dairy industry because these bacteria have caused recent outbreaks of illness and have been isolated from various dairy products in the market place. Salmonellae are generally not heat resistant and normally grow at 35 to 37 degrees C, but they can grow at much lower temperatures, provided that the incubation time is suitably extended. To minimize problems, foods should be held at or below 2 to 5 degrees C at all times. Both conventional and rapid methods are available to isolate salmonellae from dairy foods and to identify the bacteria. Salmonellae behave differently in different kinds of cheese: they survived in ripening Cheddar cheese for up to 7 mo at 13 degrees C and for 10 mo at 7 degrees C; in coldpack cheese food for several weeks, depending on the pH and preservative used; and in Domiati cheese 13 to 36 d, depending on the manufacturing process used. When Mozzarella cheese was made, temperatures of stretching and molding (60 degrees C) killed all salmonellae present, but, in cottage cheese, survival of the pathogen depended on the cooking temperature of curd. Spray drying of skim milk killed substantial numbers of salmonellae, but some survivors remained. Butter readily supported growth of salmonellae at room temperature, and neither freezing nor refrigeration for brief periods eliminated salmonellae from butter. Use of appropriate hygienic procedures, e.g., Hazard Analysis Critical Control Point system, during processing should reduce the likelihood of salmonellosis outbreaks associated with dairy foods.

Distribution, Diversity, and Seasonality of Waterborne Salmonellae in a Rural Watershed

“…While salmonellae were detected 100% (10/10) of the time when E. coli thresholds were exceeded and 84% (32/38) of the time when enterococcus thresholds were exceeded (based on the U.S. EPA single-sample limit for infrequently used bathing waters [23]), the pathogen was also found at a high frequency below the threshold standards (76% [42/55] of samples were Salmonella positive at E. coli levels of less than 576 CFU 100 ml Ϫ1 and 71% [15/21] were positive at enterococcus levels below 151 CFU 100 ml Ϫ1 ). Furthermore, neither indicator provided significant predictive value by binary logistic regression for the presence of Salmonella (all serotypes) or the clinically relevant Salmonella serotypes (all Salmonella serotypes excluding S. enterica subsp.…”

“…Patterns in serotype prevalence may be related to variable persistence in the environment, with some better suited for survival during warmer months (23,38,46,64). The increase in total serotypes detected may also be related to an overall increase in loading to the watershed during the months with the highest precipitation.…”

Evaluation of Freeze-Dried Kefir Coculture as Starter in Feta-Type Cheese Production

“…Various psychrotropic bacterial species, such as members of the genera Enterobacter, Pseudomonas, Alcaligenes, Acinetobacter, and Proteus (32), have been associated with cheese spoilage, while Escherichia coli, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus constitute the main pathogens occurring in cheeses (3,12,15,56). Recently, there has been increasing pressure on food manufacturers either to completely remove chemical preservatives from their products or to adopt more "natural" alternatives for the maintenance or extension of foods' shelf life.…”

Determination of the occurrence of plasmid virulence genes (spv) and antibiotic resistance of Salmonella strains isolated from raw milk

“…Statystycznie, najwyższa liczba zachorowań jest wynikiem spożycia jaj i produktów jajecznych, a także wyrobów cukierniczych zawierających surowe jaja. Źródłem zakażenia człowieka może być również niepoddane obróbce termicznej mleko i produkty wytwarzane z mleka surowego (4,6,10,19). W Polsce, w związku z istniejącą sprzedażą bezpośrednią i możliwą obecnie sprzedażą produktów wytwarzanych z mleka surowego w ramach rolniczego handlu detalicznego, zwiększa się ryzyko narażenia konsumenta na kontakt z patogenem.…”