Lecture 23 - Bacteriology GI/Liver 2 Flashcards
describe enterobacterales
- gram-negative rods
- facultative anaerobes
- mesophiles
- opportunistic or primary pathogens
what is the primary habitat of enterobacterales
GI tract
what is the secondary habitat of enterobacterales
soil & water
T/F: some enterobacterales ferment lactose
TRUE
T/F: enterobacterales ferment glucose to acid only
FALSE
T/F: most e. coli serotypes are non-pathogenic
TRUE
what are the 4 antigens of e. coli
- K (capsule)
- O (LPS)
- F (fimbriae)
- H (flagella)
what is the generalized pathogenesis of e. coli
- ability to attach to host cells
- efface microvilli
- invade [sub]mucosa
- produce toxins
describe enteropathogenic e. coli (EPEC)
attachment = intimin protein
effacement = loss of microvilli
reservoir = cattle
what is the impact of the secretion of effector proteins into host cells
modulate and interfere with host cells processes to promote bacterial pathogenesis
what are the unique features of EPEC
- colonize lower small intestine & colon
- attach and efface via necrosis of enterocytes and stunting of villi
- maldigestion and malabsorption
- does NOT produce toxins
describe Shiga-toxin producing (STEC) and subset enterohemorrhagic (EHEC)
attachment = intimin protein
effacement = loss of microvilli
toxin = Shiga
reservoir = cattle
summarize STEC in pigs
occurs in post-weaning (1-2 weeks)
- fimbriae adhere
- shiga toxins necrose sm and endothelial cells in vessels
- residual neurologic dysfunction and high mortality
T/F: STEC is also called edema disease in pigs
TRUE
describe enterotoxigenic E. coli (ETEC)
attachment = adhesions on pili but do not invade
toxins = LT and ST
host = calves, lambs, piglets, dogs, horses
what are the unique features of enterotoxic colibacillosis (ETEC)
- neonatal calves, lambs, and piglets
- enterocytes receptors and only present in early life
- oral infection leads to colonization of intestines
- profuse, watery, white/yellow, rancid D+
describe enteroaggregative e. coli (EAEC)
attach = biofilm and aggregates, does not invade
toxin = heat stable
host = weaned piglets and calves
describe enteroinvasive (EIEC)
attach = invade into submucosa, multiply in macrophages
host = poultry
clinical signs = bloody D+ and septicemia
what 3 things are used for the classification of E. coli
- serology
- PCR
- histopathology
how do we diagnose E. coli
- age and clinical signs
- bacterial culture
- classification
what is the general treatment for e. coli
fluids and elytes, maybe antibiotics
what strain of e. coli is zoonotic
STEC
