Shigella and Dysentery


  • Shigellae are gram-negative rods which can invade the colonic mucosa
  • Very low infective dose (~10 organisms)
  • Spread via contaminated food/flies, faecal-oral route most common
  • Can be severe
  • There are four types of shigella
    • Shigella sonnei (most common in UK- mildest)
    • Shigella flexneri (usually seen in travelers or in tropical countries, often resistant to antibiotics (as can other spp))
    • Shigella boydii
    • Shigella dysenteriae (can cause severe disease and, without treatment, death within 72 hours)

Clinical Presentation

  • In moderate-severe disease,
    • Diarrhoea, colicky abdominal pain (this can persist after the diarrhoea) and tenesmus
      • Stools are often small and blood and exudate is common, particularly after initial evacuation (after which there can be very little ‘stool’ but more blood/exudate)
    • The abdomen may be tender
    • Fever, dehydration and weakness
  • Note that it is usually self limiting, usually lasting 3-7 days


  • Stool culture/PCR
  • FBC, U&Es, LFTs


  • Rehydration therapy (oral or IV depending on severity)
  • Antibiotics (usually guided by culture/sensitivity) are not necessarily required, but can be useful in severe/prolonged cases, or in epidemics to try and prevent spread
    • Hygiene advice is important
  • NB Notify public health

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