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→Pathogenesis
===''Eschericia coli'' (''E. coli'') overview===
===''Eschericia coli'' (''E. coli'') overview===
[[File:Ecoli.jpg|200px|right]]
*Member of ''Enterobacteriacae'' family of Gram-negative bacilli
*Member of ''Enterobacteriacae'' family of Gram-negative bacilli
*'''Facultative anaerobe'''
*'''Facultative anaerobe'''
*Capsular polysaccharides produced by some strains prevent phagocytosis and interfere with complement
*Capsular polysaccharides produced by some strains prevent phagocytosis and interfere with complement
*Endotoxin is a lipolysaccharide component of the cell wall of Gram-negative bacteria, composed of lipid A, a core polysaccharide and various side chains
*Endotoxin is a lipolysaccharide component of the cell wall of Gram-negative bacteria, composed of lipid A, a core polysaccharide and various side chains
*'''Endotoxin''' is realeased when bacteria die, and causes endothelial damage leading to [[Thrombosis - Pathology#Disseminated Intravascular Coagulation|'''disseminated intravascular coagulation''']] and e'''ndotoxic shock'''; it is also a '''pyrogen'''
*'''Endotoxin''' is realeased when bacteria die, and causes endothelial damage leading to [[Disseminated Intravascular Coagulation|'''disseminated intravascular coagulation''']] and '''endotoxic shock'''; it is also a '''pyrogen'''
*Enterotoxins, verotoxins and cytotoxic necrotising factors produced by many pathogenic ''E. coli''; these produce cell damage at their site of action
*Enterotoxins, verotoxins and cytotoxic necrotising factors produced by many pathogenic ''E. coli''; these produce cell damage at their site of action
*'''Alpha-haemolysin''' may increase iron availability for invading organisms
*'''Alpha-haemolysin''' may increase iron availability for invading organisms
*'''Siderophores''' are made by certain pathogenic strains, and are responsible for iron aquisition; they include aerobactin and enterobactin
*'''Siderophores''' are made by certain pathogenic strains, and are responsible for iron aquisition; they include aerobactin and enterobactin
==Extra-intestinal infection==
==Extra-intestinal infection==
***Most common organism infecting urinary tract
***Most common organism infecting urinary tract
***Ascending infections of urinary tract
***Ascending infections of urinary tract
***Causes pyometra in the dog and cat and [[Kidney Tubulointerstitial Disease - Pathology#Pyelonephritis|pyelonephritis]]
***Causes pyometra in the dog and cat and [[Pyelonephritis|pyelonephritis]]
***Cystitis in the bitch
***Cystitis in the bitch
***Prostatitis in dogs via opportunistic infection
***Prostatitis in dogs via opportunistic infection
***Death within 24-48 hours during peracute disease
***Death within 24-48 hours during peracute disease
***Animals depressed with sunken eyes
***Animals depressed with sunken eyes
**[[Intestines Catarrhal Enteritis - Pathology#Colibacillosis|'''Colibacillosis''']]:
**[[Colibacillosis|'''Colibacillosis''']]:
***Avian:
***Avian:
****Septicaemia in newly-hatched chickens
****Septicaemia in newly-hatched chickens
***Severe depression, anorexia, salivation and abdominal distension
***Severe depression, anorexia, salivation and abdominal distension
***Morbidity and mortality high
***Morbidity and mortality high
** [[Intestines Inflammatory Bowel Disease And Related Conditions - Pathology#Histiocytic Ulcerative Colitis|Histiocytic ulcerative colitis]] in the dog and cat.
** [[Inflammatory Bowel Disease#Histiocytic Ulcerative Colitis|Histiocytic ulcerative colitis]] in the dog and cat.
** Causes [[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis in dogs]] and [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]]
** Causes [[Peritonitis - Cats and Dogs|peritonitis in dogs]] and [[Peritonitis#In pigs|peritonitis in pigs]]
**Found in [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]]
**Found in [[Osteomyelitis|osteomyelitis]]
**Associated with neonatal [[Joints Inflammatory - Pathology#In Cattle|polyarthritis of calves]]
**Associated with neonatal [[Infectious Arthritis#In Cattle|polyarthritis of calves]]
**In [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]]
**In [[Deep Pyoderma|deep pyoderma]]
**Found in [[Joints Inflammatory - Pathology#In Horses|arthritis of horses]]
**Found in [[Infectious Arthritis#In Horses|arthritis of horses]]
==Intestinal infection==
==Intestinal infection==
*''E. coli'' is part of the flora of the large intestine, but is not usually found in the small intestine
*''E. coli'' is part of the flora of the large intestine, but is not usually found in the small intestine
*Some strains possess fimbrae which attach the bacteria to the small intestinal epithelium of particular animal species
*Some strains possess fimbrae which attach the bacteria to the small intestinal epithelium of particular animal species
*''E. coli'' may cause diarrhoea via attaching and effacing lesions, where bacteria adhere intimately to the enterocyte, and cause localised effacement of the brush border microvilli; the epithelial erosion causes [[Haemorrhage - Pathology#Dysentery|dysentery]]
*''E. coli'' may cause diarrhoea via attaching and effacing lesions, where bacteria adhere intimately to the enterocyte, and cause localised effacement of the brush border microvilli; the epithelial erosion causes [[Haemorrhage#Dysentery|dysentery]]
*'''Enterotoxigenic ''E. coli'' (ETEC)''':
*'''Enterotoxigenic ''E. coli'' (ETEC)''':
**General:
**General:
*** Contributes to [[Intestines Catarrhal Enteritis - Pathology#Undifferentiated Neonatal Calf Diarrhoea|undifferentiated neonatal calf diarrhoea]], a mixed viral enteritis in calves, also known as enteric colibacillosis
*** Contributes to [[Calf Diarrhoea, Undifferentiated Neonatal|undifferentiated neonatal calf diarrhoea]], a mixed viral enteritis in calves, also known as enteric colibacillosis
***Causes scours in pigs, calves and lambs
***Causes scours in pigs, calves and lambs
***'Traveller's diarrhoea' in humans
***'Traveller's diarrhoea' in humans
*****Activates guanylate cyclase in enteric epithelial cells, stimulating fluid secretion
*****Activates guanylate cyclase in enteric epithelial cells, stimulating fluid secretion
**Clinical signs:
**Clinical signs:
***The gut becomes distended with fluid and a [[Intestine Diarrhoea - Pathology#Secretory Diarrhoeas|secretory diarrhoea]] which lasts several days results
***The gut becomes distended with fluid and a [[Diarrhoea#Secretory Diarrhoeas|secretory diarrhoea]] which lasts several days results
***Watery diarrhoea, dehydration, acidosis, death
***Watery diarrhoea, dehydration, acidosis, death
**Immunity:
**Immunity:
**Strains do not product LT or ST and are not enteroinvasive
**Strains do not product LT or ST and are not enteroinvasive
**Attaching and effacing lesions, unrelated to toxin production
**Attaching and effacing lesions, unrelated to toxin production
**[[Thrombosis - Pathology#Disseminated Intravascular Coagulation|Disseminated intravascular coagulation]] and thrombus formation
**[[Disseminated Intravascular Coagulation|Disseminated intravascular coagulation]] and thrombus formation
**''E. coli'' O157:H7 causes haemorrhagic collitis-haemolytic uraemic syndrome in humans
**''E. coli'' O157:H7 causes haemorrhagic collitis-haemolytic uraemic syndrome in humans
**Important virulence factors include toxin and fimbriae
**Important virulence factors include toxin and fimbriae
==in cattle==
*Neonatal polyarthritis:
**[[Escherichia coli|'''''Coliforms''''']]
***Localises in joints and meninges in severe non-fatal neonatal colibacillosis
***May remain as chronic arthritis in larger joints
[[Category:Enterobacteriaceae]]
[[Category:Enterobacteriaceae]]
[[Category:To_Do_-_Bacteria]]