Shigella Flashcards
What disease do Shigella bacteria cause?
Dysentery - pus and blood in the stool.
What part of the GIT does Shigellosis involve?
Superficial colonic mucosa.
Do Shigella bacteria invade any other tissues other than superficial colonic mucosa? Who are involved?
Can invade blood and organs rarely.
Immunosuppression and small children.
How are Shigella bacteria spread?
Faecal-oral route > contaminated fomites
Poor sanitation and hygiene
Over-crowding
Flies.
Name four important Shigella species.
S. dysenteriae - most severe form of disease
S. flexneri
S. boydii
S. sonnei
What kind of disease is shigellosis? Dose?
An ingestion disease.
Low infectious dose.
Outline the pathogenesis of Shigella.
Organisms reach large bowel > multiply in epithelial cells > spread into lamina propria > capillary thrombosis > death of cells
*cells also die due to accumulation of metabolic products and release of endotoxin
Pathology in Shigellosis?
- Terminal ileum/large bowel involved
- Ulceration
- Inflam response - blood + pus (polymorphs)
- Septicemia (uncommon)
What is the incubation period of shigellosis?
2-3 days
Clinical presentation of Shigellosis?
First(24 hours):
- Mild intestinal upset, no fever
Progresses to:
- Incapacitating Diarrhoea + severe fever *dehydration
- loss of blood (gelatinous clots of blood in stool)
- colic (cramping abdominal pain)
* mucus and pus in stool
How to diagnose Shigellosis?
Macroscopic - look at stool > blood, pus, mucus
Microscopic - wet prep > inflam exudate ( blood + pus cells)
Culture - organism isolated from stool
Can you get Shigellosis twice?
Yes, antibodies not as effective > thought to be due to superficial nature of lesions
How to treat Shigellosis?
Only severe cases.
Fluid replacement and antibiotics
Antibiotics used to treat Shigellosis?
Quinolones.
How to prevent the spread of Shigellosis?
Good sanitation + hygiene
Wash hands
Minimize over-crowding
