260 Case Study Exercise 31 Bacterial Counts of Food CASE STUDY Often, the most d

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260 Case Study Exercise 31 Bacterial Counts of Food CASE STUDY Often, the most difficult aspect of dissecting a foodborne is found in soil and also commonly inhabits the intestinal mining who ate what. After all, can you tracts of mammals, including humans. In addition, it is a for unch a week ago? Did you frequent contaminant of meats and gravies and is usually maybe share yours? A number of food a bite of a friend's food? Did this friend share associated with inadequate heating and cooling during the poisoning investigations have cooking process. When food products contaminated with on something as seemingly insignificant as whether Cperfringens are allowed to remain at temperatures between someone had to wait in the bar (and eat contaminated dip) 40°C and SOC (104% and 122 F), le his or her table was being readied. Every once in a vegetative cells are rapidly produced, iliness results from the while however, a situation lends itself to a quick and easy enterotoxin's action on the small intestine. C. pertringem investigation. Study the case below and answer the ques s not a particularly vinulent pathogen, but it is responsible tions that follow Food Polsoning among Inmates at a County Jail-Wisconsin, August 2008 for an estimated 250,000 cases of diarrhea annually in the United States. The vast majority of patients recover after a few days without medical intervention In instances where the number of bacteria in a sample is One August morning in 2008, a large proportion of the expected to be especially large, as would be the case with a inmates at a Wisconsin county jail awoke complaining of fecal sample, many types of specialized media may be used nausea, vorniting, and diarrhea. The local health depart. to narrow the possibilities. Selective media contain inhibl- ment suspected an outbreak of foodbome illness and, along tory substances that allow only a single type of microbe to with the Wisconsin Division of Public Health, initiated an grow, while differential media allow most organisms to grow investigation. Because of the strict routine and controlled but produce visible differences among the various microbes environment of prison ife, it was relatively easy to find out In this case, samples of the casserole the prisoners had eaten what the inmates had eaten in the past 24 hours and how were analyzed using both selective and differential media their food had been prepared. A written questionnaire di and found to contain 43,000 colony forming units (CFUs) of tributed to the inmates revealed 194 probable cases of food C.perfringens per gram of casserole. intoxication. Four respondents commented on the unusual taste of the casserole they had eaten the night before, which meals to the jail routinely froze food that was not served Investigators learned that the company distributing contained macaroni, ground beef, ground turkey, frozen and held it for up to 72 h before using it to prepare dishes vegetables, and gravy. Stool samples were obtained from for later consumption. In this case, the ground beef and six symptomatic inmates and cultured for the presence of macaroni had been cooked the previous day, and several other food items were near their expiration dates. Also, Biochemical tests of the prisoners' stool samples were proper documentation of the cooling temperatures for both negative for Salmonella, Shigello, Compylobocter, and the ground beel and the macaroni was unavailable. Inves- Escherichia coi 0157:H7. However, Clostridlium pertringenstigators concluded that improper handing of food in the enterotoxin was present in all six samples. C perfringenskitchen was responsible for the prisoners' ilness. CASE STUDY QUESTIONS 1. In this case, each gram of casserole was found to contain 43,000 colony-forming units. How many b you expect to find in an eight-ounce serving of the casserole?

Explanation / Answer

02. Gram staining shows C perfringens as a gram positive bacilli with spores located centrally or subterminally which are of bulging appearance.

03. Clostridium perfringens is normally present in the intestinal tract of humans and other animals. The feces of animals contain this bacteria. Soil is also a source of C. perfringens. As carrots are in contact with soil, consuming unclean/uncooked carrots may result in symptoms.

4. In case of food infection, a live microbe is ingested. The live bacteria takes time to acclimatise to the gut environment and starts replicating and producing toxin which results in sickness. It takes time for this. Hence the delay. Whereas in the case of food intoxication, it is not necessary that the food contains live bacteria. The food may contain toxin which was secreted by the bacteria. So, if we ingest toxin containing food, the symptoms are immediate.

Not sure of question number 1. please post it separately so that others can answer.

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