9. b. Shigella Flashcards
What is the gram stain of shigella?
Gram negative bacilli
What species of shigella is found in tropical climates?
Dysenteriae
What species of shigella is found in Ireland?
Sonnei
How does shigella infect the body?
Invades via the mucosa of the colon
Travel cell-to-cell via actin
Invades immune system
Very low infective dose
What toxins are produced by shigella?
Enterotoxin causes watery diarrhoea
Shiga toxin in s. dysenteriae serotype 1
What effect does the shiga toxin have on the body?
Inhibits protein synthesis
Causes capillary destruction and haemorrhage
Results in bowel ulceration and bloody diarrhoea
How is shigella spread?
Faecal oral; especially within households and in MSM commmunities
What is the incubation period for shigella?
24-72 hours
What are the clinical features of s. sonnei?
Profuse watery diarrhoea
Vomiting
Dehydration
What are the clinical features of dysentry?
Early= water stool, late= bloody stool
Tenesmus
What complications are associated with shigella?
Perforation and obstruction BSI in infants (dysentry) Convulsions in under 4s Reactive arthritis Haemolytic uraemic syndrome
How is shigella diagnosed?
PCR and culture of faeces
Bloods not taken as never enters blood
What are the lab features of shigella?
Non-lactose fermenting
Colourless on XLD
What is the management for shigella?
Antibiotics only given in dysentry: Ceftriaxone and ciprofloxacin
Food handlers require 48 hours of antibiotics and a negative stool sample before returning to work
What precautions are needed for salmonella and shigella?
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