Shigella

Transmission

Only found in humans

Directly: Fecal-oral route

Indirectly: Contaminated food and water.

Associated Symptoms

Sudden, severe diarrhea

Nausea, Vomiting, Fever, Colonic Inflammation (Bloody diarrhea)

Some with no symptoms but still carry the infection in their faeces

Population impacted

developing countries

160 million cases a year

60% in young children

Shigellosis-associated complications

- Malnutrition

- Bacteraemia/septicaemia (intestinal perforation)

- Dehydration

- Renal failure

- Haemolytic Uremic Syndrome (HUS)

Causative agent of bacillary dysentery

- Gram-negative, rod-shaped

- Facultative, intracellular pathogen

- Non-motile

- Highly contagious (infectious dose: 1 – 100 bacteria)

Genus Shigella: 4 species

Infection of Invasive Shigella

• Invades apical side of epithelial cells at a very low frequency. basolateral invasion much more efficient. how?

• It due to shigella gaining access via M-cells (micro-fold cells)

Infection Cont—-

1. Shigella triggers its uptake into M cells - transcytosed.

2. basolateral pocket of M cells: taken up by macrophages

3. survival in macrophages: apoptosis

4. Re-invade IEC basolaterally

Shigella intracellular Motility

Shigella released from dying macrophages subsequently enter the intestinal epithelium via the basolateral surface