What is the recommended treatment for Shigella infections?

Treatment of Shigella Infections

The recommended first-line treatment for Shigella infections is ciprofloxacin at a dose of 500mg twice daily for 3-7 days in adults, with treatment choices guided by local susceptibility patterns. 1

First-Line Treatment Options

• Ciprofloxacin is the preferred first-line agent for treating Shigella infections in adults (500mg twice daily for 3-7 days) 1
• For adults, TMP-SMX is an alternative first-line option (160mg TMP and 800mg SMX twice daily for 5 days) if the strain is susceptible 1, 2
• For children, TMP-SMX can be used at a dose of 10mg/kg/day TMP and 50mg/kg/day SMX in two divided doses for 5 days if the strain is susceptible 3, 1
• Azithromycin is an alternative treatment option for resistant strains in adults (500mg on day 1, followed by 250mg once daily for 4 days) 1

Alternative Treatment Options for Resistant Strains

• For strains resistant to first-line agents, alternative treatments include:
  • Nalidixic acid (55 mg/kg/day in four divided doses for 5 days) 3
  • Tetracycline (50 mg/kg/day in four divided doses for 5 days) 3
  • Ceftriaxone or other expanded spectrum cephalosporins 3, 4

Treatment Algorithm

1. Base initial antibiotic choice on local susceptibility patterns 1
2. For cases with unknown resistance patterns or international travel-acquired cases, fluoroquinolones are preferred as first-line treatment due to high rates of TMP-SMX resistance globally 3, 1
3. Assess clinical response within 2 days of starting treatment 3, 1
4. If no clinical improvement occurs within 2 days, change to an alternative antibiotic 3, 1
5. If no improvement occurs after an additional 2 days with a second antibiotic, refer for stool microscopy to rule out other causes such as amebiasis 3

Special Considerations

• Treatment duration:

  • For uncomplicated cases: 3-7 days 3, 1
  • For Shigella bacteremia: extend treatment to 14 days 3, 1
  • For HIV-infected patients with CD4+ counts >200 cells/μL: 7-14 days 3
  • For advanced HIV disease (CD4+ count <200 cells/μL): consider longer course (2-6 weeks) 3

• All HIV-associated Shigella infections should be treated due to higher risk of complications 3, 1

• HIV-infected persons have higher rates of adverse effects related to TMP-SMX 3, 1

Monitoring and Follow-up

• Monitor patients closely for response to treatment, defined by improvement in systemic signs and symptoms and resolution of diarrhea 3, 1
• Follow-up stool cultures are generally not required if complete clinical response has been demonstrated, except for food service workers or healthcare workers 3, 1

Common Pitfalls and Caveats

• Multiresistant strains of Shigella are widespread globally, making antibiotic selection challenging 3, 5
• Periodic antibiotic susceptibility testing is advisable in endemic and epidemic settings 3, 1
• Amebic dysentery tends to be misdiagnosed as shigellosis; consider amebiasis if two different antibiotics for shigellosis fail to improve symptoms 3, 1
• The World Health Organization does not recommend mass prophylaxis or prophylaxis of family members as a control measure for shigellosis 3, 1
• Antimotility agents are contraindicated in shigellosis 6
• Rehydration therapy should be given concurrently to prevent or correct dehydration 6, 7