Campylobacter jejuni

Question 1

What is it the leading cause of?

Answer 1

Bacterial Gasteroenteritis

Question 2

Describe the bacteria

Answer 2

Gram negative, flagella, spiraci (motility through mucus). May become spherical (coccoid) when under stress.
Survive inside and outside host cell (facultative intracellular pathogen).
Microaerophilic (opt. O2 is 5-10%)
Thermophilic (opt temp. is 37 or 42) Can live in humans and chickens.

Question 3

How long is the incubation period of infection in humans?

Answer 3

2-5 days (<500 microorganisms to cause infection)

Question 4

Where does it colonise?

Answer 4

Small Intestine and Large Intestine

Question 5

What are the symptoms of the bacterial infection?

Answer 5

Inflammation, diarrhoea (sometimes haemorrhagic), fever, nausea, cramps (cyclical, every 20 mins), intestinal ulceration and perforation observed.

Question 6

How long can the infection last?

Answer 6

5-7 days but can be fatal in immunocompromised people.

Question 7

What are the complications of Campylobacter infection?

Answer 7

Extra-intestinal spread
Guillan- Barre syndrome (GBS)
Reactive arthritis (Reiter's syndrome)

Question 8

What is GBS?

Answer 8

occurs in 1 in 100 cases
autoimmune, neuromuscular disorder.
Molecular mimicry of host gangliosides by bacteria
myelin sheath of peripheral neurones attacked
Pain, tingling, transient paralysis and respiratory arrest.

Question 9

How is Campylobacter infection diagnosed?

Answer 9

faecal sample spread on enrichment media (Bolton, Preston, Exeter) to allow Campylobacter growth. Then API or DNA sequencing to determine Campylobacter.

Question 10

How is the infection treated?

Answer 10

Rarely requires treatment.
Some antibiotics used to shorten duration of symptoms. Quinolones no longer effective due to resistance. Dehydrated patients may require IV fluid and electrolyte therapy.
GBS patients may need artificial ventilation.

Question 11

How many of the population is effected each year?

Answer 11

1% in Europe

Question 12

How do humans acquire Campylobacter?

Answer 12

consumption or handling of contaminated poultry (60-80% of cases).
Raw milk, potable water and contact with pets or wildlife.
Mud Runs
FSA survey 2015 detected bacteria in 73% of fresh chicken samples on retail sale in UK.
Cross contamination
Bacteria in deep muscle so harder to kill (BBQs)
undercooked chicken liver
Wild birds reservoir
Bird pecked milk
Direct contact with bird faeces
Lettuce

Question 13

Describe the genome of the bacteria

Answer 13

1,654 proteins, 1.64 mb
small for a bacterial genome
Plasmids can exist and harbour virulence associated genes.
High proportion of homopolymeric tracts and hypervariable sequences= genetic diversity.
Few predicted virulence factors

Question 14

Define hypervariable sequences

Answer 14

location in nuclear DNA where base pair nucleotides repeat.

Question 15

How does Campylobacter evade the host defences?

Answer 15

surface has sugar moieties
LOS- glycolipid vital for integrity of outer membrane and resistance to bile salts and other stresses.
Capsule- polysaccharide coat that may mask underlying antigens and confer resistance to phagocytosis and other innate defences.
Protein glycosylation may mask bacterial antigens

Question 16

What’s the pathogenesis?

Answer 16

evasion of host defences
colonisation of intestine
cytolethal distending toxin (CDT) implicated in damage to human intestine.

Question 17

How does the bacteria colonise the intestines?

Answer 17

flagella- motility, adhesion and injection into host cells
adhesins- surface exposed binds to fibronectin (everywhere in intestine). JlpA, CADF, FlpA.
Protein secretion systems

Question 18

What do the adhesin proteins do?

Answer 18

Mediate attachment to epithelial cells &/or extracellular matrix