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- Bacterial food-borne illness is the result of mishandling food. It includes food infection and food intoxication.
- Salmonella, Campylobacter, E. coli and Listeria bacteria in food cause food infection.
- Staphylococcus and Clostridium botulinum bacteria produce a toxin (or poison) as a by-product of growth and multiplication in food and cause food intoxication.
- Clostridium perfringens can multiply in foods to sufficient numbers to cause food poisoning.
- Sanitation and proper heating and refrigeration practices will help prevent food-borne illness.
Food intoxication results from consumption of toxins (or poisons) produced in food by bacterial growth. Toxins, not bacteria, cause illness. Toxins may not alter the appearance, odor or flavor of food. Common kinds of bacteria involved are Staphylococcus aureus and Clostridium botulinum.
In the case of Clostridium perfringens, illness is caused by toxins released in the gut when large numbers of vegetative cells are eaten.
Salmonellosis
Salmonellosis is a form of food infection that may result when foods containing Salmonella
bacteria are consumed. Once eaten, the bacteria may continue to live and grow in the intestine, set up an infection and cause illness. The possibility and severity of the illness depends in large part on the size of the dose, the resistance of the host and the type of organism causing the illness.
Salmonella bacteria thrive at temperatures between 40 and 140 degrees F. They are readily destroyed by cooking to 165 F and do not grow at refrigerator or freezer temperatures. They do survive refrigeration and freezing, however, and will begin to grow again once warmed to room temperature.
Foods commonly involved include eggs or any egg-based food, salads (such as tuna, chicken or potato), poultry, pork, processed meats, meat pies, fish, cream desserts and fillings, sandwich fillings, and milk products. These foods may be contaminated at any of the many points where the food is handled or processed from the time of slaughter or harvest until it is eaten.
Campylobacteriosis
Campylobacteriosis or campylobacter enteritis is caused by consuming food or water contaminated with the bacteria Campylobacter jejuni.
C. jejuni commonly is found in the intestinal tracts of healthy animals (especially chickens) and in untreated surface water. Raw and inadequately cooked foods of animal origin and non-chlorinated water are the most common sources of human infection (e.g. raw milk, undercooked chicken, raw hamburger, raw shellfish). The organism grows best in a reduced oxygen environment, is easily killed by heat (120 F), is inhibited by acid, salt and drying, and will not multiply at temperatures below 85 F.
Preventive measures for campylobacter infections include pasteurizing milk; avoiding post-pasteurization contamination; cooking raw meat, poultry and fish; and preventing cross-contamination between raw and cooked or ready-to-eat foods.
Listeriosis
Prior to the 1980s, listeriosis, the disease caused by Listeria monocytogenes, was primarily of veterinary concern.
As a result of its wide distribution in the environment, its ability to survive for long periods under adverse conditions, and its ability to grow at refrigeration temperatures, Listeria has since become recognized as an important food-borne pathogen.
L. monocytogenes is frequently carried by humans and animals. The organism grows in the pH range of 5.0 to 9.5. It is salt tolerant and relatively resistant to drying, but easily destroyed by heat. (It grows between 34 F and 113 F).
Preventive measures for listeriosis include maintaining good sanitation, pasteurizing milk, avoiding post-pasteurization contamination and cooking foods thoroughly.
Staphylococcal Intoxication
Staphylococcus bacteria are found on the skin and in the nose and throat of most people; people with colds and sinus infections are special carriers. Infected wounds, pimples, boils and acne are generally rich sources. Staphylococcus also are widespread in untreated water, raw milk and sewage.
When Staphylococcus get into warm food and multiply, they produce a toxin or poison that causes illness. The toxin is not detectable by taste or smell. While the bacteria itself can be killed by temperatures of 120 F, its toxin is heat resistant; therefore, it is important to keep the staph organism from growing. Keep food clean to prevent its contamination, keep it either hot (above 140 F) or cold (below 40 F) during serving time, and as quickly as possible refrigerate or freeze leftovers and foods to be served later.
Foods commonly involved in staphylococcal intoxication include protein foods such as ham, processed meats, tuna, chicken, sandwich fillings, cream fillings, potato and meat salads, custards, milk products and creamed potatoes. Foods that are handled frequently during preparation are prime targets for staphylococci contamination.
Clostridium Perfringens Food-Borne Illness
Clostridium perfringens belong to the same genus as the botulinum organism. However, the disease produced by C. perfringens is not as severe as botulism.
Spores are found in soil, nonpotable water, unprocessed foods and the intestinal tract of animals and humans. Meat and poultry are frequently contaminated with these spores from one or more sources during processing.
Spores of some strains are so heat resistant that they survive boiling for four or more hours. Furthermore, cooking drives off oxygen, kills competitive organisms and heat-shocks the spores, all of which promote germination.
Once the spores have germinated, a warm, moist, protein-rich environment with little or no oxygen is necessary for growth. If such conditions exist (i.e., holding meats at warm room temperature for several hours or cooling large pots of gravy or meat too slowly in the refrigerator), sufficient numbers of vegetative cells may be produced to cause illness.
E. Coli Hemorrhagic Colitis
Escherichia coli belong to a family of microorganisms called coliforms. Many strains of E. ColiE. coli O157:H7, causes a distinctive and sometimes deadly disease. live peacefully in the gut, helping keep the growth of more harmful microorganisms in check. However, one strain,
Ground beef is the food most associated with E. coli O157:H7 outbreaks, but other foods also have been implicated. These include raw milk, unpasteurized apple juice and cider, dry-cured salami, homemade venison jerky, sprouts, and untreated water. Infected food handlers and diapered infants with the disease likely help spread the bacteria.
Preventive strategies for E. coli infections include thorough washing and other measures to reduce the presence of the microorganism on raw food, thorough cooking of raw animal products, and avoiding recontamination of cooked meat with raw meat. To be safe, cook ground meats to 160 F.
A. Freezing temperatures stop growth of bacteria, but may allow bacteria to survive. Set freezer to 0 F.
B. Cold temperatures permit slow growth of some bacteria. Do not store raw meats for more than five days or poultry, fish or ground meat for more than two days in the refrigerator.
C. DANGER ZONE.
C-1. Some growth of food poisoning bacteria may occur.
C-2. Temperatures in this zone allow rapid growth of bacteria and production of toxins by some bacteria. Do not hold foods in this zone for more than two hours.
C-3. Some bacterial growth may occur. Many bacteria survive.
D. Warming temperatures prevent growth but allow survival of some bacteria.
E. Cooking temperatures destroy most bacteria. Time required to kill bacteria decreases as temperature increases.
F. Canning temperatures for fruits, tomatoes and pickles in water-bath canner.
G. Canning temperatures for low-acid vegetables, meat and poultry in pressure canner.
