Escherichia coli

Question 1

Describe the gram stain appearance of E. coli.

Answer 1

gram negative (pink) rod

Question 2

Name 3 E. coli virulence factors.

Answer 2

1. flagella
2. capsule
3. lipopolysaccharide

Question 3

Is E. coli part of the normal human flora?

Answer 3

Yes, normal colon commensal. Can be pathogenic both within and outside the GI tract.

Question 4

Which condition is E. coli the most common cause of?

Answer 4

UTI

Question 5

Which conditions can be caused by E. coli infection?

Answer 5

1. 5 different types of intestinal disease (depending on acquisition of specific pathogenic traits), e.g. gastroenteritis
2. UTI
3. neonatal meningitis
4. Nosocomial infections inc. sepsis, endotoxic shock and pneumonia

Question 6

How is UTI caused by E. coli treated?

Answer 6

Trimethoprim

Question 7

What is the MOA of trimethoprim?

Answer 7

Affects nucleic acid synthesis: potent inhibitor of bacterial dihydrofolate reductase, leading to a decreased availability of the tetrahydrofolate cofactors required for purine, pyrimidine, and amino acid synthesis

Question 8

How is E. coli transmitted/reach site of infection?

Answer 8

1. faecal-oral route, via contaminated food and water

2. mov. of GI commensal to other parts of body (e.g. faecal-perineal-urethral route)