Escherichia Coli

Question 1

E.coli

Answer 1

normal inhabitant of colon
extraintestinal infection (colisepticaemia)
enteric disease (special strains - ETEC)
public health (rare, special strains - ETEC)

Question 2

Enterotoxigenic Escherichia coli (ETEC)

Answer 2

watery diarrhoea - scours
enterotoxigenic
small intestine

Question 3

ETEC in calves, piglets, lambs

Answer 3

neonatal enteritis
ingestion - colonisation of lower SI
diarrhoea + stunting of villi
often with rotavirus

Question 4

2 ETEC factors for infection

Answer 4

adhesive fimbrae - colonisation

enterotoxin

Question 5

labile toxin (LT)

Answer 5

similar to cholera toxin
attaches to brush border of SI
incr cAMP, Cl- secretion - NA+ + water lost into lumen
metabolic acidosis, dehydration, electrolyte loss
can be fatal

Question 6

stable toxin (ST)

Answer 6

raises intracellular guanylate cyclase

Question 7

ETEC - diagnosis

Answer 7

on clinical grounds
faecal culture always shows e.coli
need to show toxin + fimbriae

Question 8

STEC

Answer 8

shiga-toxin producing e.coli
toxins ST-1 + ST-2
some diarrhoea + haemorrhagic colitis in calves

Question 9

STEC - public health

Answer 9

carriage by calves - beef
v.low dose infects humans
cooking destroys the pathogen

Question 10

STEC - human disease

Answer 10

haemorrhagic colitis + haemolytic uraemic syndrome - renal failure
vascular damage, oedema, thrombi
thrombotic thrombocytopaenic purpurea