8. Gastrointestinal Infection

8. Gastrointestinal Infection - 8. Common Diseases...

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Unformatted text preview: 8. Common Diseases Transmitted by Gastrointestinal Infection 2 Intoxications: diseases in which bacterial toxins are ingested in food and water Staphylococcal Food Poisoning may be most common type of food poisoning agent: Staphylococcus aureus gram +ve coccus, grows in clusters disease caused by exotoxin produced in foods during bacterial growth incubation period: 1-6 hour symptoms: restricted to intestine → enterotoxin cramps, nausea, projectile vomiting , prostration, diarrhea lasts a few hours, then rapid recovery Gastrointestinal Bacterial Intoxocation Staphylococcal Food Poisoning 3 pathogenesis: enterotoxin : toxin is among most heat-resistant of all exotoxins (resists 100°C/20 min) no obvious taste, odor or appearance Staphylococcus aureus grows from 8-45°C ( psychrotrophic ) can sometimes produce toxin in refrigerator can be in spoiled meats, dairy products, cream-filled pastries, potato salad and coleslaw (mayonnaise) Gastrointestinal Bacterial Intoxocation Staphylococcal Food Poisoning 4 reservoir: nasal cavity (sneeze) or more commonly from an abscess phage-typing can be performed to identify strain (epidemiology) Gastrointestinal Bacterial Intoxocation Staphylococcal Food Poisoning 5 Botulism agent: Clostridium botulinum gram +ve, anaerobic, spore-forming bacillus disease caused by exotoxin produced in foods during bacterial growth incubation: 1-4 days symptoms: blurred or double vision, slurred speech difficulty swallowing and chewing, labored breathing limbs lose muscle tone - flaccid paralysis may resemble stroke, Guillain-Barré syndrome, myasthenia gravis Gastrointestinal Bacterial Intoxication Botulism 6 pathogenesis: pre-formed toxin is absorbed into bloodstream affects nervous system ( neurotoxin ) powerful neurotoxin 1 pint would kill entire world population 1 ounce would kill all in USA bacteria of little consequence; unable to colonize Gastrointestinal Bacterial Intoxication Botulism 7 mechanism : toxin penetrates end brushes of nerve cells blocks release of excitatory neurotransmitter (acetylcholine) from upstream neuron no nerve impulse to muscle → no contraction respiratory paralysis and death Gastrointestinal Bacterial Intoxication Botulism upstream neuron (from brain) muscle acetylcholine neurotransmitter in vesicle electrical nerve impulse contraction signal neurotransmitter release receptor 1 2 3 4 neuro- muscular junction 3 4 8 reservoir: spores ubiquitous soil animals manure, sewage, organic fertilizers harvested products improperly canned foods honey (~25%) Gastrointestinal Bacterial Intoxication Botulism 9 transmission: C. botulinum spores germinate in improperly canned food anaerobic but not heated sufficiently to sterilize spores germinate: organism multiplies in food...
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This note was uploaded on 04/07/2008 for the course MBI 111 taught by Professor Clark during the Spring '07 term at Miami University.

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8. Gastrointestinal Infection - 8. Common Diseases...

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