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E.coli (Develop an understanding of the diversity of clinical diseases…
E.coli
Develop an understanding of the diversity of clinical diseases associated with E.coli infections :
Enteropathogenic E.coli (EPEC)
Calves and lambs
Diarrhoea - fibrin forms a row which allows them to attach tightly to the gut wall - produce a pedicel on the face of the villi
Lambs
Colibacillosis
Colisepticaemia
Watery mouth - not adequate colosstrum often - frothy mouth and listless - go down hill quickly
Calves
Neonatal diarrhoea (white scours)
Important human pathogen
Pigs
Neonatal diarrhoea
Weaning enteritis
Colibacillosis
Colisepticaemia
ETEC
Heat labile and stable toxin
Multiple adhesions - to allow sticking to gut
Main cause of traveller's diarrhoea in humans
Common in pigs
Older than 8 weeks appear to be resistant to nfecton
Extra intestinal E.coli
Calves
Colisepticaemia
Joint ill
Coliform mastitis
Lambs
Colibacillosis
Colisepticaemia
Meningitis
Avian pathogenic E.coli - APEC
Colibacillosis
Septicaemia
Omphalitis
Inflammation of the umbilical cord stump
Salpingitis - Synovitis
Coli granuloma
Swollen head
Cellulitis - don't notice until plucked -
may be to do wih a toxin
Most common cause of morbidity
and mortality mainly in broilers
Colisepticaemia
Affects birds 4-12 weeks
Domesticated and wild
Characterised by pericarditis, perihepatitis, airsacculitis, synovitis, peritonitis, conjunctivitis and enteritis
Polyserosoitis
Inflammation of many serous membrnaes
Severe fibrinous pericarditis and perihepatitis
Periarteriolar lesions in the spleen
Fibrinous thrombi in the liver
Coligranuloma - Hjarres disease (must be distinguished from mycobacteria avian)
Will present the same signs clinically and at post mortem (Older laying hens)
Yolk sac infection - transovarial
(caudal air sac to ovary)
Suppurative pericarditis
heterotrophs
Pre-disposing factors
Viral or mycoplasmal infections
Sterss (Cold shock)
Husbandry practices
Ammonia build up
Genetic susceptibility
Virulence determinants
Pilli
Type 1
Curli
P
Flagella
Iron sequestering mechanisms
Serum resistance
Acid resitancts
Dogs
Colisepticaemia
Pyometra
Urinary tract ingecions
Diarrhoea
Cat
Diarrhoea
Urinary tract infections
Horses = Neonatal diarrhoea
Rabbits
Neonatal diarrhoea:
Difficult to treat in rabbits have
many bacteria in their gut
Mastitis:
Third most common cause
Verotoxigenic
VTEC
Most strains have Flagella
Most strains are non-sorbitol fermenters
Harbours stx toxins (Shiga/VT),
large virulence plasmids,
pathogenicity island (LEE)
Attaching and effacing phenotype
Pigs
Oedema diseases in pigs
Oedema of the forehead, eyelids,
stomach wall and larynx
Not in humans
Sudden death
Ataxia, convulsions and paralysis
0139 and 0141 serotypes
Verotoxin is the main virulence determinant
Are EAE negative
Routes of infection
Humans: Ground beef
Diarrhoeal disease with kidney complications
Low infective dose <100
Commensal in ruminants
0157,026,0121,0145,0103
Can stick to plasnt cells in the same
way it sticks to intestinal cells
Factors influencing 0157 colonisation factors
LEE and putative second pathogenicity island
Same as other E.colis
Cryptic phages (genes)
90kb plasmid
Novel attachment factors
Understand the control
strategies for E.coli in animals
Economically important pathogen
in many and livestock
Cause disesae most commonly in young
animals leading to reduced growth
Live attenuated modifies for endmeic diseases
Does not protect against every strain
Not widely used as expensive
and have no benefit to the farmer
Educate the public
Reduce faecal contamination
of animals going to slaughter
Tie of rectum immediately after slaughter
, to reduce faecal contamination
Identify 'super sheders
Surveillance
Pre-probiotics
Antibiotics
Rectal application of intervention agents
Passive antibody delivery of passive immunisation
Virulence determinants of E.coli
Pili
Plasmids
Flagella
Outer membrane and secreted proteins
TTSS (Type three secretion system)
Complex allows bacteria to produce a receptors to tbe injected into a eukaryotic cell which then allows the bacteria to dock onto that cell
Acid resistance - lowering infectious dose
Serum resistance - septicaemia
Pathogenecity Islands
Groups of genes encoding function of pathogenesis
LPS - Lipopolysaccharide
Toxins
What is E.coli
Gram negative faculative anaerobic
rod shaped bacterium
Frequently motile by
peritriculous flagella
4500-5500 genes
Less genes usually means less pathogenic
Frequently carry plasmids
(Virulence, AMR)
Zoonotic some less than others
Mnay pathotypes
Culturing E.coli
Easily
done
Blood agar
Nutrient/LB agar
MacConkey agar - selects gram negative
good for isolation (colour change)
To understand the pathobiology of E.coli infections
Pathogenesis
Uropthogenic (UPEC)
P Fimbriae (Pilonephritis)
Enteropathogenic (EPEC):
Mulltiple adhesions - diarrhoea
Enterotoxigenic (ETEC):
Multiple adhesions - diarrhoea
Avian Pathogenic (APEC):
Multiple adhesins and serum resistance
Enteroaggrative (EAggEC):
Multiple adhesins, large plasmid