Toxin-producing bacterial pathogens Flashcards
what are the 3 mechanisms that pathogens can cause infection
invasive
toxin-producing
hybrids of the two above
what is the most common toxin producing pathogen species
Vibrio
of the 4 subspecies of Vibrio, what toxin producing pathogen causes the most severe disease
vibrio cholerae
what is the El tor strain, and what made it different from the previous strains
A new strain of vibrio cholera that was pandemic
-mutated the O1 antigen, new LPS serotype, encapsulated
what are the virulence factors of vibrio cholerae
flagella, pili to adhere and pili is phage encoded, meaning once the pili is expressed, the cholera toxin is phage encoded
how does the phage encoded cholera toxin affect hosts
- toxin binds to receptor activating G protein
- activates adenylate cyclase
- constant increase cAMP which stops adsorbtion of Na
- excrete Cl and get watery diarhea
what are the 2 pathogens that cause secretory diarhea (watery stool)
Vibrio and ETEC (enterotoxigenic e-coli)
what is the main pathogen that causes traveler’s diarhea
ETEC (enterotoxigenic ecoli)
what 2 toxins does ETEC produce that causes travelers diarhea
Heat-labile toxin (LT)
Heat-stable toxin (ST)
What is the difference b/w heat-labile toxin (LT) and heat-stable toxin (ST)
LT - works exactly like vibrio in that it activates adenylate cyclase resulting in secretory diarhea
ST - activates guanylate cyclase which induces cGMP causing epithelial cells to stop adsorbing Na resulting in watery stool
What are the steps to identifying which pathogen is causing secretory diarhea ?
Step 1 - rule out Vibrio cholerea
2 - inoculate plates with shit samples then
3 - grow
what animal is vibrio cholerae found in
seawater shellfish
how do you treat secretory diarhea
- ORAL rehydration
- *CANT DO IV **
- antibiotics
what two pathogens are know as “hybrid” misfits
EPEC (enteropathogeninc E-coli)
EHEC (Enterohemorrhagic E-coli)
how do EPEC and EHEC ahere to GI tissue
Intimate Adherance
what is intimate adherance and what pathogens use this to adhere to GI tissue
EPEC and EHEC use this
Stage 1 - use pili to adhere
Stage 2 - pathogen injects Tir (own protein) into host
Stage 3 - Tir binds to host’s protein intimin forming pedastool like lesion
how does hybrid misfit EPEC cause diarhea
- NO toxin*
- colonization causes (1) malabsorbtion in microvilli and (2) disruption of tight junctions from structural change when forming pedastools
how does hybrid misfit EHEC cause diarhea
Just like EPEC with malabsorbtion and disruption of tight junction BUT
has Shiga-like toxin also
what pathogen produces a toxin that can lead to hemolytic uremic syndrome ?
EHEC or enterohemmorhagic E-coli
what is the most common type of E-coli and what is its primary resovoir
EHEC (enterohemorrhagic E-coli)
-cattle
what type of toxin does hybrid misfit EHEC produce, and what does it cause
Shiga-like toxin which attacks vessels causing blood in shit
what is the best way to diagnose EHEC
blood in shit
what do you NOT treat EHEC with
antibiotics
