Updated: 7/31/2018

Shigellosis

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Snapshot
  • A 40-year-old woman presents to an urgent care clinic for multiple days of watery and bloody diarrhea and fever. She is currently homeless and has been staying at crowded homeless shelters. She also describes abdominal cramping throughout the day. On physical exam, she has sunken eyes, delayed skin turgor, and delayed capillary refill. Her abdomen is tender to palpation. A stool culture is sent and she is empirically started on antibiotics for the suspected disease.
Introduction
  • Classification
    • Shigella spp.
      • a non-flagellated, non-lactose-fermenting gram - rod
      • oxidase - and does not produce H2S
      • produces endotoxin and Shiga toxin
    • transmission
      • fecal-oral transmission
    • organisms
      • S. dysenteriae (produces the most toxin)
      • S. flexneri
      • S. boydii
      • S. sonnei (most common in the United States and least severe)
  • Epidemiology
    • incidence
      • more common in developing countries
    • demographics
      • more common in children
    • risk factors
      • ingestion of contaminated or uncooked food/water
      • travel
      • poor hygiene
      • crowding
  • Pathogenesis
    • infects gastrointestinal track through invasion of Peyer patch M cells 
      • resistant to gastric acid
    • does not spread hematogenously
    • Shiga toxin (enterotoxin)
      • "A" subunit inactivates 60S ribosome 
        • kills intestinal cells by inhibiting protein synthesis
      • is neurotoxic, cytotoxic, and enterotoxic
      • produced by S. dysenteriae
  • Associated conditions
    • shigellosis (bacillary dysentery)
    • reactive arthritis
  • Prognosis
    • symptoms occur a few days after exposure
Presentation
  • Symptoms
    • fatigue
    • malaise
    • anorexia
    • tenesmus
    • watery diarrhea precedes bloody diarrhea
      • bloody and mucoid stools
    • abdominal pain or cramping
  • Physical exam
    • fever
    • hyperactive bowel sounds
    • abdominal tenderness
    • signs of dehydration
Studies
  • Labs
    • stool culture
  • Making the diagnosis
    • based on clinical presentation and laboratory studies
Differential
  • Enteroin­vasive Escherichia coli (EIEC)
    • distinguishing factor
      • clinically very similar to shigellosis but typically less contagious and less severe
      • distinguish based on culture or polymerase chain reaction
Treatment
  • Management approach
    • antibiotics will shorten duration of dysentery
    • choice of antibiotics ultimately depends on regional resistance patterns
    • anti-motility drugs should be avoided as they may worsen symptoms
  • Conservative
    • rehydration
      • indication
        • all patients
      • modalities
        • oral
        • intravenous
  • Medical
    • antibiotics
      • indication
        • severe cases
      • drugs
        • ciprofloxacin
        • ceftriaxone
        • trimethoprim-sulfamethoxazole (TMP-SMX)
    • zinc
      • indication
        • young children
      • outcomes
        • shortens duration of disease in children
        • also improves weight gain
Complications
  • Reactive arthritis (Reiter syndrome)
    • classic triad of conjunctivitis, urethritis, and arthritis
  • Febrile seizures
 

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