E.coli

Question 1

What is the classification of E.coli?

Answer 1

Gram- negative rods
Lactose- fermenting 
Both anaerobic/ aerobic 
Motile 
Part of normal microbiota

Question 2

What does lactose fermenting mean?

Answer 2

Uses lactose as energy source
Produces lactic acid
This gives a low pH

Question 3

What are the main antigens on E.coli?

Answer 3

O (lipopolysaccharide)
H (flagella)
K (capsule)
F (fimbriae)

Question 4

How are different E.coli normally identified?

Answer 4

Via while geneome sequencing

Question 5

How does E.coli contribute to health?

Answer 5

Is part of normal bowel microbiota
Helps protect against pathogenic species
(Not normally cause disease)

Question 6

What ilnesses does E.coli cause?

Answer 6

Intestial infections (diarrhoea)

Extra-intestianl infection

• uti
• intra-abdo
• billary tract
• blood stream
• neonatal meningitis

Question 7

What E.coli cause diarrhoea?

Answer 7

ETEC
EPEC
EAEC
EIEC
DAEC
STEC

Question 8

How does ETEC cause diaeehoea?

Answer 8

Heat stable toxins
Heat labile toxins
-cause watery diarrhoea and cramping

In lower income countries

Question 9

How does diarrhoea benefit both bacteria and host?

Answer 9

Bacteria- lots of liquid & stool in host means pathogen more likely to be picked up by other cells

Host- allows flushing out of pathogen

Question 10

How does EPEC cause disease?

Answer 10

Secreates bacterial proteins into cell that then express receptor of bacteria (Tir)
Binds to Tir receptor
Recorganises host cytoskelaton

Question 11

How does STEC cause disease?

Answer 11

Breaks down RBC

Haemorrhagic colitis (bloody diarrhoea)
Haomolytic uraemic syndrome (acture renal failure, haemolyic anemia, thrombocytopenia)

Question 12

What is the action of the Shiga toxin?

Answer 12

Is endocytosed and transported into ER of host
Inactivates ribosomes
Inhibiting protein synthesis
Cell death (so bloody diarrheoa)

Question 13

What virulance factors aid extra-intestinal Ecoli infections?

Answer 13

Adhesions
Fe aquisition systems
Protectins and invasins
Toxins

Question 14

What E.colis cause UTIs?

Answer 14

UPEC

Question 15

What virulanace factors do UPEC have?

Answer 15

Adhesins: type 1 fimbriae

Toxins: Lipopolysaccharide, A-Haemolysin

Fe acquisition: increases E.coli survival

Question 16

What are the symptoms of UTIs?

Answer 16

Frequent urge to urinate 
Dysuria 
Suprapubic pain
Nocturia 
Hematuria

Question 17

What is the main cause of blood stream infectons?

Answer 17

E.coli infections spreading from another source

Knowing the origin of E.coli infection aids in treatment

Question 18

How are Diarrhoea E.coli infections managed?

Answer 18

Prevention; avaoiding contaminated sources

Treatment: non specific

• clear liquids
• oral rehydration
• avoid antibiotics

Question 19

How to treat E.coli UTIs?

Answer 19

Trimethoprim (abiotic)

In lab tests 60% seem resistant but this could be do with only untreatable cases being screened in labs

Question 20

What is the traeatment of E.coli blood steam infections?

Answer 20

Increasing resistance to antibiotics

Co-amoxiclav (go to)