What is the treatment for Enteroinvasive Escherichia coli (EIEC) infection?

Treatment of Enteroinvasive Escherichia coli (EIEC) Infection

For Enteroinvasive Escherichia coli (EIEC) infections, an extended-spectrum penicillin (e.g., piperacillin/tazobactam) or an extended-spectrum cephalosporin (e.g., ceftriaxone, cefotaxime) together with an aminoglycoside is recommended for treatment, with antibiotic selection guided by susceptibility testing. 1

Understanding EIEC Infections

• EIEC is a diarrheagenic E. coli pathotype that causes dysenteric diarrhea by invading and destroying the human colonic epithelium, similar to Shigella 2
• The pathogen carries a virulence plasmid encoding a type III secretion system that enables bacterial invasion of host cells 3
• EIEC strains are biochemically atypical compared to other E. coli - they may ferment lactose late or not at all, are lysine decarboxylase negative, and non-motile 4
• Most EIEC strains express somatic antigens that are strongly related or identical to Shigella antigens 4

Treatment Recommendations

First-line Treatment

• For EIEC infections, treatment should follow guidelines for non-HACEK gram-negative bacteria causing invasive infections 1:
  • Extended-spectrum penicillin (e.g., piperacillin/tazobactam) or
  • Extended-spectrum cephalosporin (e.g., ceftazidime, ceftriaxone, or cefotaxime)
  • Plus an aminoglycoside
  • Treatment duration: minimum of 6 weeks for invasive infections 1

Antibiotic Selection Considerations

• Antibiotic choice should be guided by susceptibility testing results 1
• For severe infections, consultation with an infectious disease specialist is recommended 1
• Treatment should be individualized based on the severity of infection and local resistance patterns 1

Alternative Treatment Options

• Ciprofloxacin may be considered as an alternative treatment option for susceptible strains 1
• For uncomplicated infections, shorter courses of antibiotics may be sufficient 5

Special Considerations

Emerging Resistant Strains

• Some EIEC strains, particularly the emerging O96:H19 serotype, demonstrate biofilm formation which may contribute to antibiotic resistance and treatment failure 3
• For infections with suspected resistant strains, combination therapy is preferred 1

Monitoring Response

• Clinical response should be monitored closely, with adjustment of therapy based on susceptibility testing 1
• For severe infections or treatment failure, consider extended duration of therapy 1

Treatment Algorithm

1. Obtain appropriate cultures before initiating antibiotics
2. Start empiric therapy with extended-spectrum penicillin or cephalosporin plus aminoglycoside 1
3. Adjust therapy based on susceptibility testing results 1
4. For mild-moderate disease: 5-7 days of appropriate antibiotics
5. For severe or invasive disease: minimum 14 days of therapy 1
6. For immunocompromised patients or those with complications: consider extended therapy (up to 6 weeks) 1

Pitfalls and Caveats

• EIEC can be misidentified as Shigella due to similar biochemical properties and antigenic characteristics 4
• Empiric therapy should cover both EIEC and Shigella until final identification is available
• Antibiotic resistance is increasing among EIEC strains, making susceptibility testing crucial 3
• The emerging biofilm-forming EIEC O96:H19 strains may require more aggressive or prolonged therapy due to potential treatment failure 3