Escherichia Coli

Question 1

What are some general features of Ecoli

Answer 1

Gram negative family - enterobacteriaceae
Motile by peritrichous flagella
Rod shaped - 2um long and 0.5um diameter
Facultative anaerobe
Energy by oxidation and reduction of organic substances
Inhabitant of intestines or warm blooded animals
Frequently commensal some cause disease

Question 2

What are true commensal

Answer 2

Symbionts

Question 3

What biosynthesis role does Ecoli play

Answer 3

Biosynthesis of vitamin K

Question 4

What groups can infections of Ecoli be

Answer 4

Intestinal - caused by diarrhoeagenic Ecoli
Extra intestinal - caused by extra intestinal pathogenic Ecoli
Pathogenic Ecoli can be grouped further into pathotypes on basis of clinical features and bacterial properties

Question 5

What are the intestinal pathotypes of Ecoli

Answer 5

Enterotoxigenic
Enterohaemorrhagic
Enteropathogenic
Enteroaggregative
Diffusely adherent
Enteroinvasive

Question 6

What are extra intestinal pathotypes of Ecoli

Answer 6

Neonatal meningitis associated Ecoli
Uropathogenic Ecoli
Avian pathogenic Ecoli
Sepsis associated Ecoli
Some cant be grouped e.g. mastitis or pyometra causing

Question 7

What are Ecoli virulence factors

Answer 7

Adhesins - pili or fimbriae
Nutrient scavenge system
Toxins - can act on gut or systemic
Secretion systems - deliver host proteins to alter function or structure of cells
Bacterial components that activate innate immunity- Lipopolysaccharide from Ecoli is potent stimulator or inflammation

Question 8

What can flagella pili and fimbriae act as

Answer 8

Adhesins
Flagella - motility
Some fimbrial types associated with increased virulence

Question 9

What is a major driver of pathogenic diversity in Ecoli

Answer 9

Horizontal gene transfer

Question 10

What are pathogenicity islands

Answer 10

Regions of DNA acquired into genome encoding virulence factors e.g. T3SS regonised by flanking genome repeats and different GC content

Question 11

What can bacteriophages do

Answer 11

Transfer of toxin genes - Stx or Shinga like toxins

Question 12

What are enterotoxins important in and what do they do

Answer 12

Important in ETEC
Damage erythrocytes leading to diarrhoea

Question 13

What do Shiga like toxins do

Answer 13

Act on blood vessels and endothelial cells
Encoded by bacteriophages (Stx1 and Stx2)

Question 14

What are Ecoli that carry Stx referred to as

Answer 14

STEC
EHEC are a class of STEC
EHEC are carried asymptomatically in cattle
Main source from beef or faecal contamination of veg/fruit
Toxin during human infection may cause haemorrhage in gut or damage kidneys

Question 15

What serotypes are pigs affected by

Answer 15

O138, O139, O141 serotypes distinct from human/cattle EHEC STEC
Toxin has range of effects in pigs - neurological damage
Toxins may lead to fluid accumulation or lesions I’m range of tissues - gut, cardio-pulmonary, brain
Oedema of face and eyelids common sign

Question 16

What does LEE stand for

Answer 16

Locus of enterocyte effacement

Question 17

What does LEE do

Answer 17

The T3SS encoded on the LEE operon is associated with colonisation of gut in cattle and enteritis in humans
Unlike salmonella SPI1 T3SS, LEE doesn’t mediate cell invasion but translocates its own receptor enterocytes - allows tight binding to gut
Effectors then inject into host cell cause actin filamentation - in distinct attaching : effacing lesions with bacterium sitting on pedestal

Question 18

What virulence factors are needed for disease with EHEC system

Answer 18

Adhesins
LEE T3SS secures EHEC to gut epithelium and elicits formation of lesions
Action of Stx-haemolytic Uremic syndrome

Question 19

What is the German 2011 bean sprout Ecoli outbreak

Answer 19

O104 is EAEC usually causes persistent diarrhoea
The German isolate acquired Stx toxin genes so because persistent
Infection common in women 15-50 unusual as EHEC is usually an infection of children and elderly
Cucumbers wrongly identified as source but did have EHEC contamination

Question 20

What is the extra intestinal disease caused by and what does it include

Answer 20

Caused by ExPEC
Includes neonatal meningitis, urinary tract and avian pathogenic pathotypes
Has distinct but variable virulence factors including invasion and systemic survival
No distinct genotype or virulence factor associated with pathotypes

Question 21

What is APEC

Answer 21

Important endemic disease in layer and broiler sector
Major cause of mortality in young broiler respiratory and systemic disease
Cause 2-4% mortality in UK broiler flock
Reproductive tract infection in mature layers
Disease from APEC pathotypes and opportunistic infection from strains in microbiota

Question 22

What do clinical presentations of avian colibacillosis include

Answer 22

Foamy air sacs (airsacculitis)
Fibrinous or caseous deposits around visceral organs including heart and liver (sometimes called Ecoli peritonitis)

Question 23

What is salpingo-peritonitis syndrome

Answer 23

Reproductive tract infection of mature layers with inflammation and fibrinous/frequently caseous deposits on ovaries or egg peritonitis

Question 24

What else may be seen in clinical presentations of avian colibacillosis

Answer 24

Peritonitis / accumulation of fluid in abdomen - ascites
Cellulitis
Septicaemia
May manifest as reduced intake of food and water, hunched posture, depression, ataxia, respiratory distress, reduced productivity

Question 25

What are the most common Ecoli infections in dogs

Answer 25

Urinary tract infections - UPEC 35-69% of UTI’s caused by UPEC
Pyometra - 19-25% bitches develop the disease by 10

Question 26

What is the cause of mastitis commonly

Answer 26

Ecoli mastitis a particular problem in housed dairy cattle over winter
Bacteria infect udder and strong inflammatory response leads to local inflammation
Excessive response to LPS can lead to systemic effects and death by sepsis/septic shock