Lesson 1.5 The Usual Suspects Definitions and templates for: Case Notes 1.5 Investigation Activity 1.5
Infections Caused by eating food containing living pathogenic microorganisms. The infection starts when the pathogenic organisms colonize the intestine. Examples of organisms that cause infection: Salmonella spp. Listeria spp. Definition
Salmonella spp. Symptoms – Diarrhea, fever, abdominal cramps – Onset 12 to 72 hours after infection – Lasts 4 to 7 days Salmonella are usually transmitted to humans by eating foods contaminated with animal feces such as beef, poultry, milk, eggs, vegetables Thorough cooking kills Salmonella Infection Example
Listeria spp. Symptoms – diarrhea, fever, abdominal cramps – if spread to the nervous system: headache, stiff neck, confusion, loss of balance, or convulsions – pregnant women: miscarriage or stillbirth, premature delivery, or infection of the newborn Infection Example
Listeria spp. (cont.) Found in soil, water, meats and dairy products, uncooked meats and vegetables, unpasteurized (raw) milk or foods made from unpasteurized milk Listeria is killed by pasteurization and cooking
Intoxication Caused by eating food containing toxins produced by bacteria or molds that were present in the food at one time. The organism does not need to be present or alive in the food (but it could be) when it is consumed, just the toxin. Toxins are poisonous substances produced by some bacteria or molds. Definition
Staphylococcus aureus Symptoms –Nausea, vomiting, stomach cramps, and diarrhea –Onset 1-6 hours after eating contaminated food Intoxication Example
Staphylococcus aureus (cont.) On skin and in the noses of up to 25% of healthy people and animals Produces seven different toxins Contamination through contact with food workers who carry the bacteria Staphylococcal toxins are resistant to heat and cannot be destroyed by cooking. Found in sliced meat, puddings, some pastries and sandwiches
Clostridium botulinum Symptoms –Double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness –Onset 18-36 hours after eating contaminated food Found in soil Usually caused by eating contaminated home-canned foods Intoxication example
Definition Toxin mediated infection Caused by eating food that contains live pathogens that make the toxin while they are alive and in the body. Examples of bacteria causing toxin mediated infection are Clostridium perfringens Escherichia coli O157:H7.
Toxin mediated infection example Clostridium perfringens Symptoms –Diarrhea, abdominal pain, occasional vomiting –Onset 8-24 hours after eating contaminated food –Resolves in 12-24 hours Found in soil, dust, water, intestines of humans and animals and improperly prepared, held, cooled, or reheated foods Prevented by thorough cooking
Toxin mediated infection example Escherichia coli O157:H7 Symptoms –Bloody diarrhea, abdominal cramps, and occasionally kidney failure –Onset 2 to 8 days after eating contaminated food –Resolves in 5 to 10 days Found on most cattle farms, in petting zoos, and can live in the intestines of healthy cattle, deer, goats, and sheep
Escherichia coli O157:H7 (cont.) Can be found in undercooked ground beef, bean sprouts, and fresh leafy vegetables such as lettuce and spinach Prevented by thoroughly cooking ground beef, avoiding un-pasteurized milk, and by washing hands carefully before preparing or eating food
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