Flashcards in Bailey Material Deck (166)
Name the 4 species of Shigella
which shgiella species causes the most severe disease?
is the shigiella inoculum size small or large?
How is acid resistance induced with Shigella?
is induced upon antibiotic growth conditions
List of five steps of invasion by Shigella
Only basolateral surface of cells are susceptible
expression of invasion plasmid antigen
lysing of phagosomal vesicles, replicate intracellularly
expression of IcsA (an ATPAse)which facilitates intracellular spread + causes actin polimerization
Describe M cells
M cells (micro fold cells) are cells found in the Peyers patches. they transport organisms and particles from the gut lien to immune cells across the epithelial barrier, and thus are important in stimulating mucosal immunity
describe ulcer formation due to Shigella
epithelial cells in the lumen die and are sloughed off causing an ulcer
describe the stool from shigella infection
Neutrophilles enter colonic tissue and can be seen in the tstoll. end result is an inflammatory diarrhea with leukocytes in stool.
what species produces shiva toxin?
describe the effects of shiva toxin
it kills intestinal epithelial cells and disrupts Na absorption (this is important bc results in watery diarrhea bc water exits cells)
whats the most common disease caused by salmonella?
what species causes Typhoid fever
salmonella Typhi and Salmonela paratyphi
what is the innoculum size for salmonella?
what is the primary virulence factor of salmonella and what induces its expression?
it expresses multiple virulence proteins found on pathogenicity islands. A low pH induces their exp.
describe the invasion process of salmonella
it invades the apical surface of intestinal epithelial cells--> causes inc. in cellular Calcium.
2.invasion occurs via bacterial mediated endocytosis
3. invasion induces "cell ruffling" and signal transduction activation and uptake into vesicles
4.salmenella travrses to the basal membrane of the intestinal epithelial cell within a vesicle
5. salmonella is released from vesicle into lamina propria where it is taken up by macrophages.
which salmonella species can replicate in the macrophage?
S. Typhoid serovars
where are S. typhi found during the carrier state?
Asymptomatic carries with colonized gallbladder
what happens when S. typhi re-infects the intestines?
causes inflammation and ulceration of peters patches which results in diarrhea hemmorages and perforation
what are the similarities between the 2 invasive enteric pathogens? (shigella and salmonella)
both are invasive, so:
1. stool is small volume
2.stool is bloody
3immune cells leukocytes in stool
4.primarily causing diseases in colon.
both are able to respond to environmental changes to know when within the host are ready to cause disease.
1.shigella able to respond to anaerobic environment to induce acid restance
2.salmonella able to respond to acidic environmen to allow expression of virulence proteins.
what are the 3 major differences b/t the 2 invasive enteric bacteria shigellla and salmonela?
1.innocluation size (acid sensitivity)
2.Bacteremia (bacteria in blood) is only seen in salmonella bc shigella is localized.
3.species causing severe disease are very dissimilar:
salmonella typhi are able to replicate within the macrophage and spread
shigella dysenter produces shia toxin
How area invasive enteric pathogens diagnosed?
based on symptoms and on stool cultures (Agar to distinguish between shigella and salmonella)
what is the 1st step in treatment of invasive enteric pathogens?
what might a doctor prescribe for salmonella gastroenteritis?
Antibiotics not indicated but 2nd generation fluoroquinolones can be used effectively
what might a doc prescribe for typhoid fever
Fluoroquinoloes or surgical removal of gallbladder
is there a vaccine for either of the invasive gram negative patrons?
generally no but there is a vaccine for capsule of typhi
what are the 6 gram negative prolific colonizers of mucosal surfaces?
what is a mucosal surface?
surface that interacts with air and has associated glands for secreting mucosa
what are the 3 defenses of mucosal surfaces?
non-specific barrier defenses
describe gram neg invasive enteric pathogen outbreak in 2011
in Germany in 2011 E-coli o103:H4 outbreak from alfalfa sprouts caused over 800 cases of Hemolytic uremic syndrome and 32 deaths