Lecture 17 - Escherichia Coli

Question 1

How can E.coli be described?

Answer 1

Gram-negative rods
Typically lactose fermenting
Often motile

Question 2

What colour does Escherichia coli stain with gram stain?

What type of bacteria are they?

Answer 2

Red/pink

Gram-negative rods

Question 3

Where are E.coli usually found?

Answer 3

In large bowel of animals + humans

Question 4

What family does E.coli belong to?

Answer 4

Enterobacteriaceae

Question 5

What family does E.coli belong to?

Answer 5

Enterobacteriaceae

Question 6

How can E.coli and other Enterobacteriaceae be differentiated from other bacteria like Pseudomonas aeruginosa?

Answer 6

E.coli = can use lactose as an energy source making lactic acid as waste (with pH indicator = pink/red)

Pseudomonas aeruginosa = non lactose fermenting (can use lactose) with pH indicator = yellow

Question 7

What are the different ways by which different species of E.coli can be identified?

Answer 7

Serology (use antibodies to detect different bacterial surface antigens)

Metabolic profiling

Genomic diversity

Question 8

How is E.coli typically transmitted?

Answer 8

Faecal-oral route:
-Faeces used as fertiliser for crops, crops not washed
-from animals to humans

Question 9

What are the 4 different serological antigens of E.coli which can be identified by serological antibodies?

Answer 9

O - LPS (Lipopolysaccharide membrane)
H - Flagella
K - Capsule
F- Fimbriae

Question 10

Where is E.coli considered normal flora?

Answer 10

Large bowel

Question 11

What is E.coli’s role in the large intestine?

Answer 11

Protects against invasion by pathogenic species like Salmonella

Question 12

What diseases can be caused as a result of E.coli?

Answer 12

Intestinal infections (diarrhoea)
Toxin-mediated disease
Extra—intestinal infections

Question 13

What are some examples of extra-intestinal infections that E.coli can cause

Answer 13

UTI
Intra-abdominal
Biliary tract
Bloodstream infection
Neonatal meningitis

Question 14

How many pathotypes of E.coli are there that cause diarrhoea?

Answer 14

6

Question 15

What are the 6 pathotypes of diarrhoeagenic E.coli?

Answer 15

Enterotoxigenic E.coli (ETEC)
Enteropathogenic E.coli (EPEC)
Enteroaggregative E.coli (EAEC)
Enteroinvasive E.coli (EIEC)
Diffusely adherent E.coli (DAEC)
Shiva toxin-producing E.coli (STEC)

Question 16

How does E.coli generally cause diarrhoea?

Answer 16

Adheres to the gut epithelia damaging them causing it to become inflamed, leading to diarrhoea

Question 17

What does ETEC stand for?

Answer 17

Enterotoxigenic E.coli

Question 18

What does STEC stand for?

Answer 18

Shiga toxin-producing E.coli

Question 19

Why can STEC be know as Verocytotoxic E.coli (VTEC)?

Answer 19

Damages vero cells

Question 20

Why can shiga toxin-producing E.coli be know as Enterohemorrhagic E.coli (EHEC)?

Answer 20

Can cause Haemorrhagic colitis (Bloody diarrhoea) and haemolytic uraemia syndrome

Question 21

What is Haemolytic uraemia syndrome (HUS)?

Answer 21

Triad of:
-acute renal failure
-haemolytic anaemia
-thrombocytopenia

Question 22

How does Shiga toxin produce symptoms/cause damage?

Answer 22

Toxin binds to Gb3 on cell
Toxin endocytosed into cell
Transported to Golgi
Fragments of toxin cleaved
Harmful fragment released into cytosol
Inactivates ribosomes inhibiting protein synthesis

Question 23

How does shiga toxin basically cause cell damage/damage large intestinal lining?

Answer 23

Toxin inhibits protein synthesis in cell

Question 24

What treatment does a patient need with Haemolytic Uraemic syndrome and why?

Answer 24

Dialysis to treat the acute renal failure

Question 25

What are extra intestinal pathogenic E.coli (ExPEC)?

Answer 25

Strains of E.coli capable of causing disease outside the intestinal tract Have a wide range of virulence factors

Question 26

What is Cystitis?

Answer 26

Urinary tract infection often caused by E.coli

Question 27

Why are UTIs more common in women?

Answer 27

Anatomical differences Much shorter journey for women from faeces

Question 28

How does Cystitis lead to Pyelonephritits?

Answer 28

Cystitis where the E.coli travels up the ureters to the kidneys

Question 29

What is the most common cause of bacterial bloodstream infection?

Answer 29

E.coli

Question 30

What are some causal factors for E.coli bloodstream infections (E.coli bacteraemia)?

Answer 30

Age Hepatobiliary infections UTIs Catheterised patients GI infections

Question 31

How are Diarrhogenic E.coli infections prevented?

Answer 31

Avoid foods and drink that could be contaminated

Question 32

How are Diarrhogenic E.coli infections treated?

Answer 32

Most infected recover in a few days Clear liquids (prevent dehydration and loss of electrolytes) Oral rehydration solutions Avoid antibiotics (may make illness worse)

Question 33

What needs to be avoided when treating Diarrhogenic E.coli infections?

Answer 33

Antibiotics (AVOID)

Question 34

How are UTIs treated?

Answer 34

Antibiotics

Question 35

What antibiotics are used to treat Urinary Tract Infections (UTI)?

Answer 35

Trimethoprim (treatment can fail if UTI is resistant to this) Nitrofurantoin

Question 36

What strain of E.coli causes travellers diarrhoea?

Answer 36

Enterotoxigenic E.coli (ETEC) By producing 2 toxins

Question 37

What is febrile neutropenia?

Answer 37

Fevers that coincide with low neutrophils

Question 38

What is the first line treatment for febrile neutropenia?

Answer 38

IV Tazocin (Piperacillin + Tazobactam) 4.5g TDS If penicillin allergic - IV meropenem 1g TDS

Question 39

What do you add to treat febrile neutropenia if there evidence of infection of the Hickman line?

Answer 39

IV vancomycin

Question 40

What type of organisms does Tazocin (Piperacillin and Tazobactam) target?

Answer 40

Gram +ve and -ve

Question 41

What type of organisms. Does vancomycin target?

Answer 41

Gram +ve