286 Microbes and You 



store the food in shallow layers not over three inches thick to 

 permit rapid cooling when the salad is placed in the refrigerator. 

 Failure to do this has been the cause of many food poisoning out- 

 breaks. A huge bowl or bucket of potato salad, as prepared for 

 large groups, may be such an efficient insulator, that the center of 

 the container may not become sufficiently cold to stop microbial 

 activity for several hours after the food is transferred to the cooling 

 chamber. Once the salad dressing has been added to the potatoes, 

 which should be thoroughly chilled beforehand, waste no time 

 in chilling the mixture in shallow layers. It is not a wise policy 

 to serve left-over potato salad a day or two later, especially if 

 it stood at warm temperatures for any period of time during the 

 first serving. Staphvlococci thrive on salad dressings, and in a 

 warm room it does not require very many hours before considerable 

 toxin can be generated in this favorable medium. 



Cream-filled bakery products— pies, eclairs, cream-puffs, etc.— 

 meat products, especiallv left-overs, gravy that is kept luke warm 

 for extended periods of time, dressings used in stuffing poultry, 

 and dairy products made from milk drawn from infected animals 

 are the usual products involved in staphvlococcus food poisoning. 

 Avoid these foods in warm weather, especially in public eating 

 establishments where what goes on in the back room is unknown to 

 the patron out in front. 



One of the characteristics of food-borne intoxications is that 

 not all persons who partake of the poisoned food are necessarily 

 affected. Each individual has his own level of tolerance for 

 poisons before he will manifest clinical symptoms, and the range 

 of tolerance is rather broad. Secondly, not all portions of the 

 food are necessarily equally poisoned. In the case of a large 

 container of potato salad, for example, those persons eating the 

 portion from the outer layers which are cooled more quicklv than 

 the center core will not get nearly as much, if any, toxin as those 

 persons who are unfortunate enough to be served that portion 

 from the depths where microbial activity might have continued 

 for hours after the container was placed in the refricrerator. 



Public health authorities can usually find the cause of an 



