Helicobacter, Vibrio, Campylobacter, Anaerobes Flashcards
What causes ulcers (Gastric and Duodenal for the most part)
Helicobacter Pylori
How is H. Pylori spread?
Fecal- Oral
Passage of Gastric Juices from human to human
H. Pylori is thought to cause what percentage of duodenal ulcers?
95%
H Pylori is thought to cause what percentage of gastric ulcers?
70%…the rest from NSAID use
Remember that H. Pylori can predispose to cancer because of the almost constant metaplasia
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Name the H. Pylori virulence factors
- VacA encodes “Vacuolating Cytotoxin”
- Cag
- Urease
- PAI (Pathogenicity associated Island)
What is VacA?
Vacuolating cytotoxin punches holes in endosomes and lysosomes which leads to cell death.
What is Urease?
Urease is secreted by H. Pylori because it neutralizes the acidic environment of the stomach
What is Cag?
rearranges the cytoskeleton
What is a Pathogenicity Associated Island?
A PAI is a big chunk of DNA that can be inserted into the bacterial chromosome. In the case of H. Pylori it encodes a type III secretion system which can bring in things from the outside
What is the morphology of H. Pylori?
Slender gram negative rods with flagella
Microaerophillic– just want a little bit of air, almost anaerobic
What actually causes the ulcers in H. Pylori infection
Its a combination of the cell destruction from VacA, Cag, and immune response
Dx of H. Pylori
- Endoscopy with biopsy and culture
- Urea Breath test
- Serology
What’s the most common bacterial infection in developed nations
Campylobacter jejuni
How would you come into contact with Campylobacter?
Undercooked poultry and unpasteurized milk, also contaminated water
morphology of campylobacter?
Seagull shape (spiral) gram negative rods Like H. Pylori they are also microaerophillic
Incubation period of camp?
1 week
Clinical presentation of camp
- fever with apendicitis like pain.
- watery diarrhea that progresses to dysentery with blood and pus
Antecedent to Guillain Barre?
Remember that Guillain Barre is rising paralysis. Campylobacter is the most common antecedent to Guillian Barre. Thought to be related to lipooligosacharides from the camp mimicing myelin and the body developing an antibody to it.
How long does Camp usually last>
3-7 days
Vibrio looks like what?
Curved gram negative rods with a motile flagella
THEY ARE OXIDASE POSITIVE
Vibrio = oysters…commonly found in warm saltwater
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significant vibrio?
Vibrio cholerae
Vibrio parahaemolyticus
Vibrio Vulnificus
Cholera spread how
Contaminated water and food
Cholera serogroups are based on what
O antigen
How many serogroups of cholerae are there>
Over 200
Which serogroups are responsible for epidemic and pndemic cholera
O1 and O139
O1 serogroup divided into what two biotypes?
- El Tor
- Classical
20 liters a day
thats terrible
Incubation period of cholera
2-3 days
Remember, it takes a high infectious dose of cholerae to infect someone because the bacteria has a hard time making it through the stomach and into the lower bowel.
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rice water stool
cholerae
Virulence factors of cholerae?
- PAI encoded pillus
- Phage encoded toxin (AB Toxin) remember it activates adenylate cyclase and then cAMP which opens chloride channels
Cholerae diagnosis
stool culture on TCBS
Cholerae treatment?
oral hydration therapy + doxycycline or erythromycin
V. Parahaemolyticus
- Free-living in sea water
- Seafood associated food poisoning
- most common seafood illness in japan
- Gulf and Pacific coasts of US
- Watery diarrhea with cramps, nausea, vomitting
V. Vulnificus
Free living in sea water as well
- raw oysters or wound infection
- vomitting, diarrhea, abdominal cramps
- IC pts can become septic
- Rare but 20% fatal
What do anaerobes lack that prevents them from being able to survive in the presence of oxygen species?
Superoxide dismutase (SOD) and Catalase
How do anaerobic bacteria derive their energy?
From carbohydrate fermentation or breaqkdown of AAs
Most common anaerobic infection?
Bacterioides Fragilis
What is the morphology of Bacterioides Fragillis?
Gram negative Coccobacillus
Has an antiphagocytic capsule which means it can also infect the lungs
Prevotella Melaninogenica
Gram negative coccobacillus
Anti-phagocytic capsule
Gram Positive Spore forming rods?
Clostridium
These are the only anaerobic spore forming bacteria
Large Boxcar gram positive rods
Clostridium Perfringens
Gas Gangrene caused by
Clostridium Perfringens
How does Gas Gangrene come about
You get a contamination of a wound by the C Perfringens spores
Gas comes from?
carbo fermentation
C. Perfringens food poisoning
pretty common
Vibrio are oxidase?
Oxidase Positive
Vibrio Cholerae attach to small intestine epithelium via TCP
Toxin co-regulated pillus (TCP)
