L19 - Escherichia coli

Question 1

Describe the structure of E. coli

Answer 1

Gram negative rod/faculatively anaerobic/typically lactose fermenting (pink colonies on MacConkey agar)

Question 2

Pseudomonas aeruginosa is a non-lactose fermenting member of the enterobacteriaceae (E. coli is a fermenting membrer). What colour do colonies of this grow on MacConkey agar?

Answer 2

Yellow

Question 3

What are the following strains of E. coli responsible for?
ETEC
EPEC
UPEC (a ExPEC)
Other ExPEC's

Answer 3

ETEC - traveller’s diarrhoea. Toxins cause the insestines to secrete excess fluid

EPEC - Bloody diarrhoea

UPEC - UTI

OTher ExPEC’s - perotinitis/septicaemia (sepsis) /neonatal meningitis

Question 4

What is the outline for treatment and prevention for diarrhoeagenic E. coli?

Answer 4

Prevention - avoid easily contaminable foods like raw fruit and veg. meat, dairy products, running water.

Treatment - Clear liquids, rest, NO antibiotics

Question 5

What is the treatment for neonatal meningitis?

Answer 5

IV ceftoxamine

Question 6

What is the treatment for all of E. coli infections apart from neonatal meningitis and diarrhoeagenic E. coli strains?

Answer 6

Trimethoprim and if resistant nitrofurantoin

Question 7

Name two virulence factors of uropathogenic E. coli

Answer 7

Adhesins/ toxins/iron acquisition

Question 8

What test in a dipstick test would indicate E. coli causing the infection rather than a gram positive organism?

Answer 8

Presence of nitrites