Lesson 8b: Escherichia coli Flashcards
motile w/ peritrichous flagella
the cells of E.coli is composed of _____ that is used as antigens in serotyping E.coli;
lipopolysaccharide
this 3 are used for serotypic E.coli
Somatic (O)
Flgellar (H)
Capsular (k)
are protein in nature & the capsular antigens are composed of polysaccharide
Flagellar antigens
is present in many strains & act as adhesins facilitating attachment to mucosal surface
Proteinacious fimbrial (F) antigens
what are the predisposing factor thet permit colonization
- age
- immune status
- nature of diet
- heavy exposure to pathogenic strains
this interfere w/ the phagocytosis & with the antibacterial effectiveness of the complement system
capsule
released upon lysis or death of bacteria & endotoxin shock is a significant in septicaemia
endotoxin
endotoxin produce this _____ the lead to endothelial damage leading to disseminated intravascular coagulation
pyrogenic activity
this allows the attachement to mucosal surface & facilitate colonization by diminishing the expulsive effects of peristalsis & flushing of effect urine.
fimbrial adhesion
what is the adhesins of pigs that is present in E.coli
K88
adhesins of calves present in E.coli
F41
adhesins of calves & lambs present in E.coli
K99
what is the receptor found in older pigs, that is important in postweaning diarrhea & oedema disease
F18
this adhesins is associated in effacing E. coli that produce characteristics attaching & effacing lesion in which the bacteria are intimately adherent to the host epithelial cell membrane w/ marked rearrangement of the cytoskeleton
intimin
what are the 2 types of enterotoxin?
- heat labile (LT)
- heat stable (ST)
LT1 his is found in pigs, induces hypersecretion of fluid into the intestine tru stimulation of?
adenylate cyclase activity
LT2 is demonstrated in some ETEC strains isolated from ?
cattle
STa (heat stable a) is isolated from porcine, bovine, ovine & human speciemes. Toxins stimulate fluid & electrolyte secretions into small intestines & inhibits fluid absorption from the intestine by increasing?
intracellular guanosine monophosphate
in STb it causes secretion of this 2 ions & inhibit the absorption of this 1 ion
- chloride ion & bicarbonate ion
- sodium ion
produces heat-labile enterotoxin (LT) and/or heat-stable enterotoxin (ST). These toxins cause diarrheal illness by affecting the intestinal epithelial cells, leading to watery diarrhea.
Enterotoxigenic E.coli (ETEC)
In ETEC this 3 can cause secretory diarrhea tru Chloride ion & bicarbonate ions secretion & inhibition of sodium ion absorption
LT, STa & STb
They form characteristic “stacked-brick” biofilms on intestinal epithelial cells. Diarrhea in animals
Atypical (EAggEC)
They form characteristic “stacked-brick” biofilms on intestinal epithelial cells. Diarrhea in humans
Typical EAggEC
What are the 2 major toxins identify in Typical EAggEC
- East I
- Plasmid-encoded toxin
what is the major adhesins of E.coli producing oedema disease in pigs?
F18 fimbraie
this toxins in oedema in pigs contribute to disease damage & increase vascular permeability, that will lead to fluid accumulation & edema formation
Stx2e & alpha haemolysin
what are the 4 E.coli strains associated w/ extraintestinal disease
- Avian pathogenic E. coli (APEC)
- Strains causing localized infections
- Septicaemic E. coli (SEPEC)
- Europathogenic E. coli (UPEC)
what is the several adhesin of APEC?
- adherence pili
- long polar fimbrial
- non-fimbrial adhesins
In APECS presence of this contributes to resistance to humoral immunity
Capsular antigens
what are the 2 toxin include in APEC
- endotoxin
- temperature-sensitive haemogglutinin
What is the virulence factor of APEC
Aerobactin iron uptake system
In Septicaemic E. coli what is the 2 adhesins that are found on the surface antigen in calves
- fimbrial
- CS3IA
What are the toxin produce in SEPEC?
- endotoxin
- CNF (cytotoxin necrotizing factor)
- CDF ( cytolethal distending factor)
what is the major predisposing factor of SEPEC?
hypogammaglobulinemia
what is the resistance mechanism of SEPEC, that contribute to the resistance of ciruculating antigens?
- capsular antigen
- Smooth LPS
Europathogenic E. coli can cause ?
UTI & pyometra if left untreated
what is the major adhesins of UPEC?
type I, P & S fimbiraie
UPEC produces this 2 toxins
Alpha-haemolyisn & CNF-1
what are the suitable specimen in cases of pyometra or metritis?
midstream urine and cervical swabs
Specimens cultured on blood and MacConkey agar are incubated aerobically at
37°C for 24 to 48 hours
On blood agar, colonies are:
greyish, round and shiny with a characteristic smell, may be haemolytic or non-haemolytic
On MacConkey agar, colonies are;
bright pink
The colonies of some E. coli strains have a _____ _____on EMB agar.
Metallic sheen
______ _____ may be necessary to identify isolates from coliform mastitis or cystitis
Biochemical profile
When enterotoxigenic strains of E. coli are suspected, the presence of either
enterotoxins or fimbrial antigens can be confirmed by:
immunological methods or molecular techniques such as PCR
Enterotoxins in the small intestine can be detected, using methods employing:
monoclonal antibodies.
For expression of fimbrial antigens, isolates should be subcultured on:
Minca medium
Fimbrial antigens can be identified using:
ELISA or latex agglutination.
PCR techniques using _____ ____ for genes encoding heat- labile and heat-stable enterotoxins may be used to identify enterotoxigenic strains of E. coli
primer specific