Escherichia Coli (E.coli)

Question 1

What bacteria is shown in the following gram stain?

Answer 1

E.coli: Gram Negative rods

Question 2

Where does e. coli form part of the bpdy’s microbiota?

Answer 2

Large bowel

Question 3

E.coli can use sugar lactose as an energy source.

What does it produce as a waste product?

Answer 3

Lactic acid

Question 4

Name some infections which can be caused by E. coli. (in general terms)

Answer 4

• Intestinal infections
• Toxin-mediated disease
• Extra-intestinal infections
  
  • Urinary tract
  • Intra-abdominal
  • Biliary tract
  • Bloodstream
  • Neonatal meningitis

Specific disease causing strains of E coli

Question 5

How many pathotypes of diarrhoeagenic bacteria are there?

Answer 5

6

Question 6

What is ETEC?

Answer 6

Enterotoxigenic E coli

Question 7

What is the leading cause of travelers’ diarrhoea?

Answer 7

• ETEC (Enterotoxigenic E coli)

(common in lower-income countries)

Question 8

How is ETEC transmitted?

Answer 8

Faeco-oral transmission

Question 9

What toxins does ETEC produce?

Answer 9

Heat-stable (ST)

Heat-labile (LT)

Question 10

How does ETEC cause symptoms?

Answer 10

Toxins stimulate lining of intestines

–> causes them to:

• Secrete excessive fluid

Question 11

What are the symptoms of an ETEC infection?

Answer 11

1. Watery diarrhoea
2. Abdominal cramping
3. Fever
4. Nausea
5. Vomiting
6. Loss of appetite
7. Headaches
8. Muscle aches
9. Bloating

(Less common)

Question 12

How long does it take for the onset of symptoms from an ETEC infection and how long does it usually last?

Answer 12

Onset: 1-3 days

Lasts: 3-4 days

Question 13

What is EPEC?

Answer 13

Eneteropathogenic e.coli

Question 14

What is does STEC stand for?

Answer 14

Shiga toxin-producing E.coli

Question 15

What does STEC cause?

Answer 15

1. Haemorrahgic colitis (bloody diarrhoea)
2. Haemolytic uraemic syndrome (HUS= acute renal failure, haemolytic anaemia and thrombocytopenia)

Question 16

Are there some strains of e.coli which are capable to causing disease outside of the GI tract?

Answer 16

Yes

Question 17

How do e.coli eneter the bladder?

Answer 17

Uropathogenic e.coli

Transferred from rectum to urethra

Migrate to bladder

Cause cystitis

Question 18

Differentiate betwen e.coli and pyelonephritis

Answer 18

Question 19

What is the mechanism for infection of uropathogenic e. coli? (UPEC)

Answer 19

• Adhesins:
  
  • bind to proteins on uroepithelium
  • Mediate adhesion, invasion of uroepithelium, formation of intracellular bacterial communities
• Toxins:
  
  • LPS (lipopolysaccharides)
  • alpha Haemolysin

Question 20

Why might e.coi be the commonest cause of bloodstream infections in the UK?

Answer 20

Patients usually 75+

Use of urinary catheters

Question 21

Which antibitics are commonly used to treat E.coli infections?

Answer 21

• Trimethoprim
• Nitofurantoin