Lec 06: Bacterial Pathogens in GI Disorders Flashcards
Most important enterobacteriaceae antigen.
O antigen. This elicits IgM
Antigen that imparts virulence
K antigen
Antigen that is found on the flagella
H antigen. This elicits IgG
most abundant facultative anaerobe in the colon
E. coli
Most common type of E.coli
Enterotoxigenic E. coli (ETEC)
Most common type of E.coli
Enterotoxigenic E. coli (ETEC)
What is the mode of action of heat labile toxin?
sub-unit B attaches to Gm ganglioside of brush
border cells of small intestines to facilitate sub-unit A entry
Sub-unit A: increases cAMP concentration via
activation of adenylate cyclase -> extreme
and prolonged hypersecretion of water and
chloride, while inhibiting sodium reabsorption -> dehydration -> electrolyte imbalance
What is the mode of action of heat stable toxin?
STa activates guanylate cyclase in enteric
epithelium -> stimulates fluid secretion
What symptoms do you expect from Enteroinvasive E. coli ?
severe abdominal cramps/pain,
malaise, fever and bloody stools
What symptoms do you expect from Enteroinvasive E. coli ?
severe abdominal cramps/pain,
malaise, fever and bloody stools
What symptoms do you expect from Enteropathogenic E.coli?
severe, watery diarrhea with
dehydration and shock in CHILDREN
Enterohemorrhagic E. coli (EHEC) produces what kind of toxin?
Shiga toxin
EHEC is (Sorbitol+,Sorbitol-)
Sorbitol -
Represent more than 99.5% of salmonella strains.
subspecies I
Source of salmonella infection
contaminated food and drink (ie. Dried or frozen eggs, Meat and meat products)
Tests done for detection of Salmonella
Widal test (obsolete), TyphiDot
Treatment for Salmonella infection
- ampicillin
- trimethoprim-sulfamethoxazole
- 3rd gen cephalosporin (i.e. cefixime)
Treatment for Salmonella infection
- ampicillin
- trimethoprim-sulfamethoxazole
- 3rd gen cephalosporin (i.e. cefixime)
T or F. Shigella has human reservoirs
True
What are the outcomes of severe Shigella infection?
invasion of submucosa, Pseudomembranous enterocolitis
Biochemical Properties of Shigella
- lactose non-fermenters
- non-motile
- fermentation of carbohydrates without gas
production
Treatment of Shigella
Ciprofloxacin
What is the temperature of growth for Campylobacter?
42 degC
biochemical analysis results for Campylobacter
oxidase (+), catalase (+), (+) hippurate hydrolysis
biochemical analysis results for Campylobacter
oxidase (+), catalase (+), (+) hippurate hydrolysis
T or F. VIbrio cholerae are Facultative anaerobes
True
Laboratory diagnosis of Vibro cholerae
thiosulfate citrate bile salt (TCBS) plate held
for 48 hours
What is the laboratory diagnosis of H.pylori?
Chocolate agar or Skirrow agar
What is the treatment for H.pylori?
Bismuth salt +2 antibiotics
Main cause of food poisoning
Bacilus cereus
Why can Bacilus cereus can grow in adverse conditions?
They produce spores
Lab diagnosis of Bacilus cereus
produce colonies on BAP and Gram +
