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29 Cards in this Set
- Front
- Back
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Name 3 diseases caused by H. pylori
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Chronic, asymptomatic gastritis
Gastric carcinoma Peptic ulcer disease |
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Gram-negative spiral-shaped
rod with a tuft of flagella at one end • Produces urease (hydrolyzes urea to CO2 and ammonia) • Withstands low pH of the stomach • Colonizes the mucosal epithelium of stomach (antrum) of about 50% of humans |
H. pylori
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How is H. pylori most likely
acquired? 1. From your dog 2. At birth from mom 3. Consuming contaminated water or food 4. Contact with stool or vomit and possibly saliva of an infected person 5. It is not contagious |
2. At birth from mom
3. Consuming contaminated water or food 4. Contact with stool or vomit and possibly saliva of an infected person |
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Causes more than 90% of duodenal
ulcers and up to 80% of gastric ulcers |
H. pylori
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Patient presents with abdominal discomfort described is dull and gnawing. This has been going on for several weeks. It occurs 2-3 hours after meals and is relieved by eating or popping antacid meds
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Peptic Ulcer
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Describe H. pylori pathogenesis leading to an ulcer
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Ingested bacteria swim through mucus layer
• Attach to mucus secreting cells and multiply, triggering inflammation and impairing the cells’ ability to make protective mucus • Changes in gastric physiology: increased gastric acid and pepsinogen production - Acid erodes stomach lining and there is a strong inflammatory response |
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What do mucous cells release to attract PMNs during H. pylori infection?
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IL-8
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Name the H. pylori virulence factors
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- Motility
-Urease --> neutralizes gastric acid, converts Co2 to ammonia (protects from acid) -Adhesins --> promote colonization - Phospholipase A2 --> breaks down membrane lipids -->DAMAGE -CagA --> disrupts tight jxns, IL-8, actin cytoskeleton rearrangement -VacA--> forms pore in membrane, attacks mitochondria --> APOPTOSIS |
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Name two lab tests for H. pylori
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C13 urea breath test
Fecal Antigen Test |
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Why does vomiting occur so quickly with ingestion of Staph. aureus laden foods.
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No bacterial colonization or germination required, ingest pre-formed toxin
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Do you see fecal leukocytes in
bacterial toxin-mediated food-borne disease? |
No!
It's self limiting |
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Common Vehicles:
Fried rice, vanilla sauce, cream meatballs, boiled beef, BBQ chicken |
Bacillus cereus
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Common Vehicles:
Ham, pork, canned beef, cream-filled pastry |
Staph. aureus
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Primarily effect nervous system shortly after ingesting preformed toxin in foods
Gram-positive, cocci |
Staph aureus
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Primarily effect nervous system shortly after ingesting preformed toxin in foods
Gram-positive rod, sporeforming aerobe, motile |
Bacillus cereus
(AEROBE) |
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Primarily effect nervous system shortly after ingesting preformed toxin in foods
Gram-positive rod, spore-forming anaerobe (terminal spores), motile |
Clostridium botulinum
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Most common type of food poisoning in US
Emetic dose is 1-25ug!!! |
Staph aureus
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Pathogenesis of Staphylococcal Enterotoxins?
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Enterotoxin ingested → stimulate chemoreceptors in gut wall → afferent nerve to vomit center in brain → vomiting and diarrhea within 2-6 hours
(This is quick because you are ingesting a pre-formed toxin!) |
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• Produces an emetic toxin when spores germinate in food –primarily associated with cooked rice
• Resists low pH and stable to heat • Toxin = activates adenylate cyclase, similar to cholera toxin • Clinically resembles Staph food poisoning– causes vomiting in 2-6 hours • Uncommon in US |
Bacillus cereus
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Spores are ubiquitous in nature and germinate in food under anaerobic conditions (ex. during home canning)
• Release potent neurotoxins • Rare food-borne disease but it is the most lethal of all the bacterial toxin-mediated food-borne diseases |
Clostridium botulinum
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Adult disease (due to ingestion of neurotoxin)
– Nausea, vomiting, dizziness → cranial palsy, double vision, swallowing difficulties → respiratory paralysis and death |
Clostridium botulinum
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What is the mechanism by which
the botulinum toxin causes a flaccid paralysis? |
Inhibits release of ACh
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How does the tetanus toxin cause spastic paralysis?
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Toxin blocks inhibitory interneurons
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Infant disease – due to immature immune system
• Ingested spores germinate in intestine and elaborate an exotoxin causing constipation and generalized weakness (floppy baby syndrome) • Avoid feeding babies honey |
C. botulinum
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_____ suppresses
release of inhibitory neurotransmitters (GABA and glycine), therefore signals are unopposed and muscles are constantly stimulated to contract |
Tetanospasmin: Clostridium tetani
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Which bug did we recently study
that can persist in the gallbladder of carriers? |
Salmonella typhi
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Cholecystitis is due to ______
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Obstruction (gallstones)
(Allow stasis which lead to bacterial infection!) |
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Common etiologies of Cholecystitis?
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E. Coli
Klebsiella/Enterobacter Enterococcus |
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What's the big deal about chronic bacterial infection of the bile and gallbladder?
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Bacteria can produce carcinogenic precursors leading to gallbladder carcinoma!
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