E coli Flashcards
some characteristics of enterobacteriacae
- gram neg
- facultatively anaerobic
- rod-shaped
how do enterobacteriacae metabolise?
-ferment glucose to acid and gas
is enterobacteriacae oxidase pos or neg
oxidase neg
do enterobacteriacae ferment lactose?
some do and some dont
what is the habitat of enterobacteriacae
GI tract, soil, water
what is the mode of infection of enterobacteriacae
by ingestion
which enterobacteriacae ferment lactose?
- escherichia
- enterobacter
- klebsiella
what enterobacteriacae do not ferment lactose
- morganella
- proteus
- salmonella
- serratia
- yersinia
MacConkey Agar is selective for what?
- selects gram neg
- gram pos are inhibited
how do you tell lactose pos or neg on a MacConkey agar plate?
- lactose neg - golden
- lactose pos - pink
what is the metabolism of Escherichia coli
-facultative anaerobe
-lactose fermenter
(pink colonies on macconkey agar)
true/false: some strains of Escherichia coli are hemolytic
true
Escherichia coli is a normal inhabitnat where?
- soil and water
- lower intestinal tract
where are H antigens on Escherichia coli
flagella
-heat labile, protein
where are O antigens on Escherichia coli
cell wall
-LSP, heat stable
where at K antigens on Escherichia coli
capsule
-CHO or protein
where are F antigens on Escherichia coli
pilus
-protein (plasma coded)
what is serotyping
classification of bacteria within a species based on antigenic structure
what does the O antigen designate?
somatic
what are Escherichia coli broadly classified into?
- intestinal pathogenic E. coli (IPAC)
- extraintestinal pathogenic E. coli (ExPAC)
what is virotyping (pathotying)
classification based on virulence factors
what are the 5 categories of pathogenic E. coli based on?
- patterns of attachment on host cells (sinlgy or aggregates)
- effects of attachment on host cells (none or destruction)
- production of toxins
- invasiveness
enteropathogenic (EPEC)
- attachment is pili mediated
- loss of microvilli (effacement)
- invasion and structural changes
- prodce cytotoxin
- cause diarrhea in humans, rarely in animals
Attaching and Effacing or Enterohemorrhagic (AEEC, EHEC, STEC, VTEC)
- attachment is mediated by a protein, Intimin (NO PILI)
- loss of microvilli (effacement)
- invasion and structural changes
- ***produces Shiga toxin (Stx)
characteristics of Shiga Toxins
- biologially and structually resemble the cytotoxin of Shigella dystenteriae
- heat labile
- lethal to vero cells (hence verotoxin, VTEC)
what are the two types of shiga toxin
- Stx1
- Stx2
*know about Stx2e
it is involved in edema disease in swine
where are the genes Stx1 and Stx2 located?
on a temperate bacteriophage
how do shiga toxins work?
they inhibit protein synthesis
what are shiga toxins a concern
-cytotoxic to enterocytes and vascular endothelial cells
what is the most common serotype of Escherichia coli
E. coli O157:H7
characteristics of enteroinvasive (EIEC)
- multiply inside the cell (salmonella-like)
- invasion and cellular destruction
- cause bacterimia or septicemia
- mostly seen in poultry
characteristics of enterotoxigenic (ETEC)
- ‘cholera-like’
- attach (pili mediated)
- produce enterotoxins
- heat labile
- heat stable (100C for 30 min)
what doe LT stand for?
cholera-like
enterotoxin LT
- has 2 polypeptide chains and B (A-B toxin)
- B subunit binds to the intestinal epithelium
enterotoxin ST
-small proteins
-Sta (methanol soluble)
Stb (methanol insoluble)
what does STa cause?
induce fluid accumulation in the instestine of suckling mice
what does Stb do?
does not cause fluid accumulation in the intestine of suckling mice
characteristics of enteroaggregative (EAbbEC)
- form aggregates
- do not invade
- produce ST-like (heat stable) called EAST and hemolysin-like toxins
what is cytotoxin necrotizing factor producing E. coli (CNF-PEC)
- attach but do not invade the cells
- produce a toxin that causes necrosis
- reported to cause diarrhea in calves pigs and humans
what does extraintestinal pathogenic E. coli (ExPEC) cause
-strains cause septicemia mastitis, infections of the uterus, urinary tract or air sacs (poultry)
what are the three forms of colibacillosis?
- diarrheal: mild to severe, with or without blood
- septicemic: colisepticemia
- localized: suppurative
what are the two locations of collibacillosis?
- intestinal
- extraintestinal
what is the mode of infection of E. coli
- ingestion
- inhalation
- direct infection
what are the three forms of colibacillosis in SWINE?
- neonatal enteritis
- weanling enteritis (post weanling diarrhea)
- edema disease
what strain causes weanling enteritis?
-caused by hemolytic strains (EPEC)
what strain causes edema disease?
caused by AEEC (EHEC)
-Stx (Stx2e) is the major virulence factor
whawt are predisposing factors to edema disease?
- age 7-10 days after weaning
- change of feed
- rapid growth
- diarrhea
what are the clinical signs of edema disease?
edema: eyelids, facial area, stomach, mesenteric lymph nodes, colon, gall bladder, larynx etc
how do you prevent edema disease?
- separation of sick pigs
- antibiotics in the feed (enrofloxacin
what are clinical signs of colibacillosis in calves?
- diarrhea “white scour” during the first week of life
- feces full of gas bubbles
what is the virulence factor of colibacillosis in calves?
enterotoxins (STa)
what is the septicemic form of colibacillosis in cattle?
- in calves deprived of colostrum
- virulence factor: endotoxin
- endotoxic shock and death
what is a common E. coli infection of cows in adult cows?
mastitis
what are clinical signs of mastitis?
swelling of udder, discolored milk, blood clots, loss of milk production
pagenesis of mastitis in cows
entry through teat adherence to mammary cells release of endotoxin absorption of endotoxin release of cytotoxin
what happens to adult horses with colibacillosis?
mares- abortion; acute mastitis
what are the clinical signs of colibacillosis in fouals?
fever, rapid pulse, dullness and weakness
-(no enteritis!)
how do you see colibacillosis in dogs and cats?
diarrhea is not common
- commonly isolated from genital and urinary tract infections
- females - cystitis and pyometra
- males - prostitis
what are the virulence
- pili - adherence
- hemolysin
- cytotoxin necrotizing factor
- protease enzyme
colibacillosis in poultry
- diarrheal disease is rare
- localized or systemic
- avian pathogenic E. coli
do avian strains of colibacillosis cause diseases in other animals?
no
what is coli-granuloma (hjarre’s disease) in poultry
chronic form of bacillosis with granulomatious lesions in the walls of the intestinal tract, liver and lungs
what does colibacillosis cause as a respiratory disease in poultry?
air-sacculitis
what is cellutitis?
infection of the subcutis
what can celluitis cause in poultry?
swollen head syndrome
when making a presumptive diagnosis, what do you look at?
- age of the animal (neonate)
- clinical signs (diarrhea with or without blood)
is E. coli present in all fecals?
yes! need to know if it is a pathogenic strain or not
