What is the treatment for Shigellosis?

Treatment of Shigellosis

The first-line treatment for shigellosis is ciprofloxacin 500mg twice daily for 3-7 days in adults, with alternative options including azithromycin or TMP-SMX based on local susceptibility patterns. 1

Antibiotic Treatment Algorithm

First-line Treatment Options:

• For adults:

  • Ciprofloxacin 500mg twice daily for 3-7 days (preferred first-line agent) 1, 2
  • TMP-SMX 160mg/800mg twice daily for 5 days (if strain is susceptible) 3, 1
  • Azithromycin 500mg on day 1, followed by 250mg once daily for 4 days (for resistant strains) 1, 4

• For children:

  • TMP-SMX 10mg/kg/day TMP and 50mg/kg/day SMX in two divided doses for 5 days (if strain is susceptible) 3
  • Azithromycin (for resistant strains or when fluoroquinolones are contraindicated) 1, 5
  • Ceftriaxone or cefixime (as alternatives recommended by the American Academy of Pediatrics) 5

Second-line Options (for resistant strains):

• Nalidixic acid 55mg/kg/day in four divided doses for 5 days 3
• Tetracycline 50mg/kg/day in four divided doses for 5 days (not for children under 8 years) 3

Treatment Decision-Making Process

1. Base initial antibiotic choice on local susceptibility patterns 1

   • For travel-acquired cases, consider high rates of TMP-SMX resistance 1
   • Fluoroquinolones are preferred when resistance patterns are unknown 1, 6

2. Assess clinical response within 48 hours 3, 1

   • If no clinical response occurs within 2 days, change to another recommended antibiotic 3
   • If no improvement after an additional 2 days with second antibiotic, refer for stool microscopy to rule out amebiasis 3, 1

3. Duration of treatment:

   • Standard course: 3-7 days for ciprofloxacin, 5 days for other agents 1, 7
   • For Shigella bacteremia: extend treatment to 14 days 1

Special Considerations

• Multiresistant strains: Shigella strains have become increasingly resistant to multiple antibiotics globally, necessitating periodic susceptibility testing 3, 8
• HIV-infected patients: All HIV-associated Shigella infections should be treated due to higher risk of complications; note that HIV-infected persons have higher rates of adverse effects related to TMP-SMX 1
• S. dysenteriae type 1: This species produces more severe disease and may require longer treatment courses compared to other Shigella species 8, 7

Common Pitfalls and Caveats

• Misdiagnosis: Amebic dysentery is often misdiagnosed as shigellosis. Consider amebiasis if two different antibiotics for shigellosis fail to improve symptoms 3, 1
• Inappropriate prophylaxis: WHO does not recommend mass prophylaxis or prophylaxis of family members as a control measure for shigellosis 3, 1
• Inadequate follow-up: Monitor patients closely for response to treatment, defined by improvement in systemic signs and symptoms and resolution of diarrhea 1
• Premature cessation of therapy: Complete the full course of antibiotics even if symptoms improve rapidly 1
• Single-dose therapy limitations: While single-dose ciprofloxacin may be effective for some Shigella species, it is inferior to multi-dose therapy for S. dysenteriae type 1 7

Supportive Care

• Rehydration therapy: Reduced osmolarity oral rehydration solution is recommended as first-line therapy for mild to moderate dehydration 3
• Nutritional support: Continue feeding during illness to maintain nutritional status 3
• Infection control: Implement appropriate hygiene measures to prevent transmission, especially in healthcare settings and among food handlers 6