Vibrio/Campylobacter/Helicobacter Flashcards
What are the characteristics of non-inflammatory diarrhea?
No fecal WBC’s, small intestine, watery diarrhea
What are some of the causes of non-inflammatory diarrhea?
- Toxigenic bacteria, e.g. enterotoxigenic E. coli, V. cholerae
– Produce toxin affecting chloride secretion and sodium absorption
- Viruses cause death of enterocytes
- Protozoa in small bowel
- Bacteria – preformed toxin in food
What are the characteristics of inflammatory diarrhea?
Fecal WBC’s, large intestine, low volume of stool with mucus, blood and pus
What are some of the causes of inflammatory diarrhea?
- Bacteria – Shigella, Campylobacter, E. coli
- Protozoa – Entamoeba histolytica
- Toxin – Clostridium difficile, enterohemorrhagic E. coli
What is the adherence factor of V. cholera?
Tcp pili – Toxin coregulated pili
What conditions does V. cholera grow in?
Alkaline conditions
What are some characteristics of the metabolism of V. cholera?
Facultative anaerobe
Oxidase positive
What are the functions of ToxT/R/S for cholera?
- ToxS–membrane sensor
- ToxR–activates a number of genes including ToxT
- ToxT–activates tcp group and others
What is the main origin place of most cholera?
India and SE Asia.
What amount of cholera ingested is required for inoculation?
10^8 which is a relatively high amount
What is the mechanism of the cholera toxin?
ADP-ribosylating toxin that leads to the constant activation of AC which produces excess amounts of cAMP. cAMP promotes the secretion of Cl- and will inhibit the absorption of Na+ and Cl-
What is an important mediator of cholera immunity?
IgA
What are the clinical manifestations of cholera?
- Nonspecific prodrome: abdominal discomfort
vomiting, loose stools
- PROFUSE WATERY DIARRHEA
- No fever
- Stool is clear, odorless, “rice water”
How is oral rehydration for cholera achieved?
Administration of glucose alongside electorlytes
What antibiotic is used to treat cholera?
Doxycycline in most countries. Azithromycin for women and children.
What are the non-cholera Vibrio species associated with?
Shellfish
What are some of the characteristics of Campylobacter jejuni?
Microaerophilic
Oxidase positive
Biochemically inactive
Grow better at 42°C than 37°C
What is the main reservoir and route of infection for Campylobacter jejuni?
Poultry mainly
What is the inoculum required for infection with C. jejuni?
Relatively low
What is C. jejuni infection associated with?
Guillain Barre Syndrome which is an ascending muscle paralysis from axonal degeneration and demyelination
Is C. jejuni invasive?
Yes
What are the clinical manifestations of C. jejuni infection?
Three day incubation followed by fever, abdominal PAIN, with blood and pus in stool
What is the treatment for C. jejuni infection?
Treatment with erythromycin, azithromycin or ciprofloxacin
- Ciprofloxacin resistance is increasing
What are the characteristics of Helicobacter pylori?
Microaerophilic
Oxidase positive
UREASE POSITIVE
Non-oxidative, non-fermentative
What is the significance of urease in H. pylori?
Urease positivity used for testing and by the bacteria
to allow it to survive in the harsh environment of the stomach
What is the action of the H. pylori cytotoxin?
Exotoxin inserts into cell membrane and forms pore releasing nutrients. It targets mitochondrial membrane and releases cytochrome C and induces apoptosis.
What is the treatment for H. pylori?
Combination of proton pump inhibitor and two antibiotics (amoxicillin, clarithromycin, metronidazole, tetracycline) for 10-14 days
What are the clinical manifestations of H. pylori infection?
Persistent colonization of gastric mucosa causing inflammation
What diseases is H. pylori associated with?
Causes gastritis, gastric and duodenal ulcer, mucosa- associated B-cell lymphoma (MALT), gastric cancer
How is H. pylori diagnosed?
Diagnosed with invasive (biopsy) and non invasive (breath, stool antigen and antibody) tests
