Gi infections 2 - C jejuni

Question 1

C jejuni - describe the pathogen

Answer 1

Opportunistic foodborne pathogen.
Spiral (spirochete) shaped (may become coccoid under stress); Bi-polar flagella.
Gram negative.
Facultative intracellular pathogen (survives inside and outside of host).

Microaerophilic (optimum O2 for growth 5 -10%); thermophilic (37-42 ℃)
Colonises the intestinal mucosa.

Question 2

Transmission of c jejuni

Answer 2

Zoonotic infection (transmitted to humans by animals/animal products).
Main route of C. jejuni transmission raw or undercooked poultry.

Other routes: pork, beef and contaminated (untreated) drinking water.

Direct (faecal-oral route) or indirect transmission (food).

Question 3

Mechanism of infection – C. jejuni

Answer 3

evasion of host defence:

Lipooligosaccharide (LOS): a glycolipid vital for integrity of the outer membrane and resistance to bile salts. Can display molecular mimicry of host structures.

Capsule: a polysaccharide coat that may mask underlying antigens and confer resistance to phagocytosis & other innate defences.

Protein glycosylation (adds carbohydrate moiety to a protein):
May mask bacterial antigens. Hides them from immune cells (PAMPs = phagocytosis)!

Question 4

Infection in humans: Campylobacteriosis

Answer 4

Incubation period of ca. 2-5 days after ingestion (infectious dose may be < 500 cells).

Small & large intestines colonised.

Inflammatory diarrhoea, sometimes haemorrhagic (blood from damaged vessels).

Fever, nausea, abdominal cramps & pain are common.

Usually self-limiting & symptoms typically last5-7 days.

Intestinal ulceration & perforation observed in some cases.

Question 5

what can c jejuni cause

Answer 5

gullain barre syndrome = death

Question 6

Enrichment & detection of Campylobacter

Answer 6

TYPICALLY NEED A FAECAL SAMPLE
Enrichment media (e.g., Preston, Exeter or Bolton broth) may contain:
Ferrous sulphate, sodium metabisulphate & sodium pyruvate to quench toxic compounds & increase aerotolerance.
Lysed horse blood to quench oxygen & provide a source of iron
Antibiotics: vancomycin, cefoperazone, trimethoprim.
We can do Identification – API, DNA sequencing.

Question 7

Treatment

Answer 7

Can give erythromycin
If dehydrated give fluid and electrolytes therapy
Generally self limiting though