Exam 4- Lecture 15 P3 Flashcards
What is food poisoning?
the ingestion of food containing microbial toxins
- microbes do not grow in the host
- will just run its course
What is food infection?
the ingestion of food containing viable pathogens
- microbes grow in host & cause damage/diasease
- possibly need more active treatment
What are the common causes of food poisoning?
- staphylococcus
- clostridium
What are the common causes of food infection?
- salmonella
- campylobacter
- listeria
What are two characteristics of staphylococcus aureus that allow the bacteria to grow on food products?
gram-positive and facultative aerobe
What does staphylococcus produce?
enterotoxins
- variable among S. aureus strains
- heat stable (prevents degradation)
What are the sources of exposure to staphylococcus aureus?
- meat, poultry, and cream-filled desserts
- onset 1-6 hours, duration 48 hours
What are two characteristics of clostridium spp. that allow the bacteria to grow on food products?
- spores survive canning/cooking
- germinate in storage
What does clostridium spp. produce?
toxins:
- C. perfringens– enterotoxin
- C. botulinum– botulin toxin
* all from canned food
What are the sources of exposure to clostridium spp.?
-C. perfringens (most common)- onset 7-15 hours, duration 24 hours
- C. botulinum (dangerous)- canned goods
What are the treatment and prevention strategies for food poisoning?
- supportive treatment in extreme cases (fluids & electrolyte replacement)
- sanitation of food production, preparation, and storage
What are two characteristics of salmonella that allow the bacteria to infect food?
gram-negative and facultative aerobe
- 2nd most common bacterial food infection
What pathogenesis does salmonella have?
- diverse virulence factors
- severe cases- typhoid fever
What are the sources of exposure to salmonella?
chronic carriers- typhoid Mary
What are two characteristics of campylobacter spp. that allow the bacteria to infect food?
gram-negative and microaerophile
- most common bacterial food infection
What pathogenesis does campylobacter spp. have?
inflammation of intestinal epitherlium
What are the sources of exposure to campylobacter?
- resident in poultry intestines (90%)
- antibiotics in severe cases
What are two characteristics of listeria monocytogenes that allow the bacteria to infect food?
gram-positive and facultative aerobe
- acid, salt, and cold tolerant
What is the most severe bacterial food infection?
listeria monocytogenes
- 20% of foodborne illness deaths in the US
What pathogenesis does listeria monocytogenes have?
- infection cycle
- severe cases: septicemia and meningitis
What are the sources of exposure to listeria monocytogenes?
unpasteurized dairy and prepackaged foods
What are the 5 steps of the infection cycle of listeria monocytogenes?
- Phagocytosis by macrophage
- Lysis of phagosome, replication
- Actin-based motility
- Invasion of adjacent cell
- Repeat
