Psychrotrophic pathogens

Szabo, E.A., Scurrah, K.J. and Burrows, J.M. (2000) Survey for psychrotrophic pathogens in minimally processed lettuce . Letters in Applied Microbiology, 30, 456 -60. 

Sheldon, B., Schuman, J., 1996. Thermal and biological treatments to control psychrotrophic pathogens. Poultry Science 75, 1126—1132. 

With sterilised products, only chemical deterioration limits the shelf-life as microorganisms are not involved. With spore-containing products the germination of spores must be inhibited. With pasteurised products, refrigeration must be adequate or spoilage will be rapid it is possible that psychrotrophic pathogens that survive pasteurisation or are added by post-... 

Milk may be thermized (c. 65°C x 15 s) on receipt at the factory to reduce bacterial load, especially psychrotrophs, which are heat labile. Since thermization does not kill pathogens, thermized milk is usually fully pasteurized before cheesemaking. 

In products prepared without pasteurization, nonsporeforming as well as sporeforming pathogens should be considered as potential hazard. With mildly cooked minimally processed food, the pathogens of greatest concern are the psychrotrophic nonproteolytic types of Clostridium botulinum and certain strains of B. cereus [74]. 

Similar surveys, though on a much smaller scale, have demonstrated that another enteric pathogen. Yersinia enterocolitica, may well play a role not unlike that of salmonellae, if control measures are not taken at any early stage The aggravating factor in this instance is the psychrotrophic character of this species of the Enterobacteriaceae. This will lead to its relatively rapid growth on meats stored at chill temperatures and its enrichment in cold stores. Thus its epidemiological pressure may become very high. 

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