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Infection 2023 > E-coli > Flashcards

E-coli Flashcards

1
Q

Full na,e

A

Escherichia coli

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2
Q

Gram stain

A

Negative rods (red stain)

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3
Q

Microbe type

A

Anaerobic
Motile (flagellum)
Part of large bowel microbiota (multiple serotypes)

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4
Q

Family type E-coli

A

Enterobacteriales

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5
Q

What does one health ecology of ecoli mean?

A

Present in animals, humans and environment
Transmission can occur between these
Challenges with resistant serotypes

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6
Q

Ecoli under micorscope

A

Gram negative rods
Pile up and form colonies (from division)

(ribosome, nucleoid, plasma membrane)

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7
Q

How E-coli identified in lab?

A

MacConkey Agar - contains lactose and pH indicator

E-coli use lactose sugar as fuel and produce lactic acid waste product (decreases pH, turns indicator pink)

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8
Q

MacConkey Agar e-coli result

A

Lactose fermenting so stains PINK

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9
Q

How are different e-coli’s typed?

A

Serology (antibodies and antigens)
Metabolic profiling
Genomic diversity (whole genome sequencing, DNA hybridisation)

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10
Q

Antigens present on e-coli

A

K - capsule
O - lipopolysaccharide wall
F - fimbriae
H - flagella

(KOFH)

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11
Q

Genetic diversity of e-coli

A

IMMENSE

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12
Q

E-coli function large bowel

A

Large bowel microbiota (humans & animals)

Protects against invasion of pathogenic species (salmonella)

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13
Q

What can e-coli cause?

A

Intestinal infections (diarrhoea)

Extra-intestinal infections:
UTI
Biliary tract
Intra-abdominal abscess
Blood stream infection

NEONATAL MENINGITIS

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14
Q

What determines pathology of e-coli?

A

Presence of virulence factors on specific e-coli strains

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15
Q

How does e-coli invade?

A

Different ways depending on subtype/strain

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16
Q

Six causes of e-coli diarrhoea

A 
Entero:
toxigenic e.coli (ETEC)
pathogenic (EPEC)
aggregative (EAEC)
invasive (EIEC)
Diffusely adherent (DAEC)
Shiga toxin producing (STEC verocytotoxin producing/haemorrhagic)
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17
Q

Most common diarrhoea e.coli children of developing world

A

Enteropathogenic

Enteroinvasive

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18
Q

Immunocompromised e.coli

A

EAggEC

19
Q

Enterotoxigenic e.coli

A

Travelers diarrhoea

Faecal-oral

20
Q

What toxins does ETEC produce? What do they do?

A

Heat stable toxin (ST)
Heat labile toxin (LT)

stimulate lining to secrete excessive fluid = diarrhoea and cramping

21
Q

Less common ETEC symptoms

A 
Fever
Nausea
Loss of appetite
Headache 
Muscle aches
Bloating
22
Q

When does ETEC resolve?

A

Onset 1-3 days

Lasts 3-4 days

23
Q

How does EPEC attach and enter enterocytes?

A

Destroys microvilli - attaches
Type 3 mediated secretion of bacterial proteins
Tir (bacteria receptor translocated into infected cell)
Allows intimate binding

24
Q

What do EPEC proteins to when translocated to cell?

A

Signals to reorganise host actin-cytoskeleton

Form pedestal like structures under the adherent bacteria

25
Q

What does EPEC bind to?

A 
Tir inserted into enterocyte
Pedestal formed (anchor EPEC)
EPEC binds to intimin on pedestal
26
Q

What is shiga toxin producing e.coli? (STEC)

A

Verocytotoxic/enterohemorrhagic e.coli

27
Q

What does STEC cause

A

Haemorrhagic colitis (bloody diarrhoea)

Haemolytic uraemic syndrome - HUS TRIAD:
Renal failure, haemolytic anaemia, thrombocytopenia

28
Q

STEC first outbreak

A

O157:H7

Oregan/Michegan - 1982
Eating at fast food restaurant - tracked back

29
Q

Molecular action of shiga toxin

A

B subunits bind to Gb3
Toxin endocytosed
Goes to golgi and endoplasmic reticulum
A chain cleaved (A1 and A2 held by disulfide bond until ER)

A1 part inactivates ribosomes
Inhibits protein synthesis
= cell death

30
Q

E.coli O157 scotland 2016

A

3 year old - primary case, died
Dunsyre blue cheese
Unpasteurised cows milk = vehicle for infection

31
Q

Shiga toxin germany 2011

A

Contaminated bean sprouts

Women affected more than men

32
Q

Extra-intestinal e.coli virulence factors

A

Adhesins
Iron acquisition systems
Protectins/invasins
Toxins

33
Q

UTI and e.coli who?

A

Common in women
Anatomical differences (rectum –> urethra)
Shorter distance in females

34
Q

Cystitis/pyelonephritis clinical symptoms

A 
Frequent and urgent urination
Dysuria (burning)
Suprapubic pain 
Nocturia
Haematuria
Malaise
35
Q

Uropathogenic e-coli adhesins

A

Type 1 fimbrae adhesive tips

bind a-D mannosylated proteins on uroepithelium

36
Q

Uropathogenic e.coli toxins

A

Lipopolysaccharide

a-haemolysin - cytotoxic towards epithelial cells

37
Q

Uropathogenic e.coli iron acquisition

A

Iron is restricted in urinary tract

Bacteria produce iron-complexing proteins (siderophores) to get iron

38
Q

Causes of blood stream infections

A

E-coli most common in england

UTI, Urinary catheters, heaptobiliary infections, GI infections

39
Q

Where do blood stream infections occur UK?

A

50% higher in north of England BUT more common in warmer times of year (north is colder)

40
Q

Emerging e.coli blood stream infections

A

Type 131
Type 69
- some resistant to antibiotics

41
Q

Managing e-coli infections diarrhoea

A

Avoid contaminated foods/drink

Raw fruits and veg avoid

42
Q

Treatment diarrhoea e.coli

A

Clear liquids - prevent dehydration
Oral rehydration solution (sodium, glucose, water_
Avoid antibiotics - diarrhoea protective

43
Q

Antibiotics UTI

A

Trimethoprim (increasing resistance or are samples to lad unrepresentative of majority?)
Nitrofurantoin

44
Q

Why is resistance occuring e-coli?

A

Bacteria so have plasmids - resistance genes can be horizontally transferred

40-50% resistant to co-amoxiclav
Carbapenemase genes arising (carbapenem resistant)

Infection 2023 (29 decks)

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