E. Coli Flashcards
Escherichia characteristics
gram negative coccobacilli, lactose positive, oxidase negative, motile rods. major pathogen. very diverse species.
Shigella are taxonomically also escherichia (only present in humans)
Pathogenicity is strain dependent
Intestinal and extra-intestinal infections
E. coli serotype
O26, K60, F41, H11
E coli virulence factors
cell-associated: endotoxin, capsule, fimbrial adhesins, non-fimbrial adhesins
extracellular: enterotoxins, cytotoxins, siderophores
Enteric pathotypes E coli
ETEC - enterotoxigenic EPEC - enteropathogenic EHEC - enterohemorrhagic VTEC - verotoxigenic RPEC - rabbit pathogenic
extra-intestinal pathotypes E coli
APEC - avian pathogenic NTEC - necrotoxigenic (cattle) Mastitis-causing E coli - cattle MMA - pigs UPEC - dogs (uropathogenic)
ETEC piglets - virulence factors
neonatal: F4, F5, F6 F41, STa, STb. Non-hemolytic
Neonatal - 3 weeks: F4, LT, STa, STb, EAST1. Hemolytic
Post-weaning: F4, F18, LT, STa, STb, EAST1. hemolytic
ETEC piglets pathogenesis
ETEC is found in the intestine of healthy sows. Break in equilibrium between passage to piglets and maternal antibodies = disease. Break in equilibrium may be due to high infection pressure, lowered maternal immunity or appearance of a new type
ETEC piglets diagnosis
CS, age, very smelly feces, dehydration, older piglets have white-grey diarrhea, culture, detection of virulence factors via PCR/agglutination.
ETEC piglets treatment
hydration, antimicrobials
ETEC piglets prevention
keep infection pressure low and maternal immunity high.
Good hygiene, vaccinate sows (2 doses, second 2-6 weeks pre-partum), vaccinate piglets for post-weaning diarrhea, selection for F4 receptor-free piglets
VTEC piglets (edema disease) virulence factors
F18 - adhesion to small bowel
Exotoxin - VT2e or Stx2e (BV necrosis)
Endotoxin - acute mortality
VTEC piglets pathogenesis
sow to piglet transmission
weaning causes stress + change in intestinal flora
excretion –> increased infection pressure –> contamination of other piglets
Toxin productions causes enterorrhagia (hyperacute), high BV permeability (acute), intravascular coagulation (slow)
endotoxin causes shock and acute mortality
VTEC in piglets diagnosis
CS (3 weeks post weaning - acute mortality, diarrhea, anorexia, edema), bacteriology and confirmation of virulence factors
VTEC in piglets treatment
affected animals: fasting to eliminate toxin, antimicrobial therapy
not-yet-affected: antimicrobial therapy
VTEC in piglets prevention
reduce stress at weaning, starter feed before weaning, good fibre content in feed, adaptation of intestinal flora (probiotics, organic acids, zinc oxide), vaccination 2-4 days old, select for pigs that are F18-receptor negative
EPEC in pigs virulence factors
BFP - bundle forming pili, initial attachment
attaching and effacing: intimate attachment (eae)
T3SS - translocates bacterial effector proteins into target cell
EPEC in pigs diagnosis
bacterial isolation and detection of eae gene
EPEC in pigs treatment
oral antimicrobials
EPEC in pigs prevention
no vaccine, little is known to prevent
E. Coli UTIs in pigs predisposing factors
hygiene, water intake, obstipation, age, individual differences
E. Coli UTIs in pigs diagnosis
CS (anorexia, hematuria, vaginal exudate), bacteriology
E. Coli UTIs in pigs treatment
culling, antibiotics for 3 weeks
MMA or PPDS in pigs etiology
metritis-mastitis-agalactiae, post partum dysgalactiae syndrome
hereditary, hormonal, feed, infectious (e. coli)
Bovine ETEC virulence factors
in animals less than 3 days old. Adhesion via fimbriae - F5, F41, F17, CS31A, also has STa and STb toxins
Bovine ETEC pathogenesis
disruption of equilibrium due to:
colostrum (too little, too late, too low in antibodies) or infection (too early, too high)
Bovine ETEC diagnosis
ELISA, culture and virulence gene detection, agglutination/PCR
Bovine ETEC therapy
separate sick animals, hydration, antibiotics (lots of resistance!!!), NSAIDs
on milking farms: separate calves from mothers, colostrum from multi-parturient animals, antibiotics per os, vaccination of cows, antibodies per os
Bovine EPEC
not common. virulence due to eae.
Age: 1-8 weeks
CS: mucoid diarrhea, may have blood in stool, mainly LI infection
Therapy: antibiotics
STEC/VTEC/EHEC in bovines
only of zoonotic importance. virulence genes: eae, stx1, stx2 best known serotype = O157;H7 responsible for serious infection leading to death or persistent kidney disease AKA hemorrhagic uremic syndrome
Bovine NTEC virulence
ExPEC, facultative pathogenic
virulence factors: serum resistance, iron uptake systems, endotoxin, capsule, adhesion factors, CNF1 and CNF2 toxins
Bovine NTEC pathogenesis
uptake: per os or by umbilical cord causes septicemia which leads to: hyperacute: acute mortality, shock acute: general symptoms, fast mortality slow: polyarthritis, pneumonia, pleuritis, meningoencephalitis
Bovine NTEC diagnosis
clinical signs (age, low gamma globulins in serum), isolation and PCR for virulence genes
Bovine NTEC treatment
NSAIDs, antibiotics, gamma globulins from older animals
Bovine NTEC prevention
make sure that the calves get good quality colostrum
Bovine E. Coli mastitis
no known virulence factors, environmental origin. gram - = animal has fever frequently lost udder quarter Prevention: hygiene Treatment: systemic antibiotics
E. coli enteric disease in dogs
frequently coinfection with other pathogens
ETEC, EPEC, VTEC, EIEC - both in clinically healthy as well as diarrheic
Puppies - CNF1 e. coli
Cystitis dogs and cats
dog: fimbriae type 1, F12, F13. Specific serotypes (O2, O4, O6, O83). 50% are alpha-hemolytic
Cat: very rare
treatment: check for underlying causes, broad spectrum antibiotics
Pyometra
seen in dogs. treatment = surgery and antibiotics
same strains as cystitis
APEC general
facultative pathogen. most important bact disease in broilers and layers. extra-intestinal disease - septicemia-colibacillosis
APEC virulence
serotypes: O1, O2, O78
virulence factors: fimbriae/pili, iron capturing systems, serum resistance
APEC clinical appearances
neonatal - colibacillosis
respiratory - colibacillosis and septicemia
egg yolk - peritonitis
scabby hip/necrotic dermatitis
APEC diagnosis
pathological lesions, isolation of E. coli from internal organs, serotyping (O1, O2, O78)
APEC treatment
very difficult, antibiotics (susceptibility tests necessary)
APEC prevention
hygiene, stress, temperature, vaccine
RPEC diagnosis and treatment
eae positive.
D: CS, isolation and subtyping. PCR on eae
T: antibiotics, care
