Should I cover for Enterococcus (E) faecalis in a patient with feculent peritonitis?

Antibiotic Coverage for Enterococcus faecalis in Feculent Peritonitis

Empiric anti-enterococcal therapy is recommended for patients with feculent peritonitis, particularly in healthcare-associated infections, postoperative infections, and in patients who have previously received cephalosporins or other antimicrobial agents that select for Enterococcus species. 1

Indications for Anti-enterococcal Coverage

Healthcare-Associated Peritonitis

• Antimicrobial therapy for enterococci should be given when enterococci are recovered from patients with healthcare-associated intra-abdominal infections 1
• Enterococci are more prevalent in healthcare-associated infections (22.3%) compared to community-acquired infections (13.9%) 1
• In a retrospective study of patients with secondary peritonitis treated in ICU, Enterococci were isolated in 47.1% of all patients, making them the most prevalent bacteria among aerobic Gram-positive isolates 1

High-Risk Patient Populations

• Empiric anti-enterococcal therapy is specifically recommended for patients with:
  • Postoperative infections 1
  • Prior exposure to cephalosporins or other antimicrobials selecting for Enterococcus species 1, 2
  • Immunocompromised status 1, 2
  • Valvular heart disease or prosthetic intravascular materials 1, 2
• The presence of Enterococcus species, particularly in polymicrobial peritonitis, has been associated with worse outcomes 1

Antibiotic Selection for E. faecalis Coverage

First-Line Options

• Initial empiric anti-enterococcal therapy should be directed against Enterococcus faecalis 1
• Recommended antibiotics for E. faecalis coverage include:
  • Ampicillin 1, 3
  • Piperacillin-tazobactam 1
  • Vancomycin (for ampicillin-resistant strains) 1, 4

Special Considerations

• For biofilm infections, a combination of ampicillin-ceftriaxone is recommended as it effectively targets biofilm-embedded bacteria 3
• For ampicillin-resistant Enterococcus (ARE), vancomycin is the treatment of choice 4
• For vancomycin-resistant Enterococcus faecalis, linezolid or tigecycline are appropriate options 1, 5

When Not to Cover for Enterococcus

• For community-acquired biliary infections, antimicrobial activity against enterococci is not required, as the pathogenicity of enterococci has not been demonstrated in this specific context 1
• Empiric therapy directed against vancomycin-resistant Enterococcus faecium is not recommended unless the patient is at very high risk, such as:
  • Liver transplant recipients with intra-abdominal infection originating in the hepatobiliary tree 1
  • Patients known to be colonized with vancomycin-resistant E. faecium 1

Clinical Impact and Outcomes

• Studies have shown that the presence of Enterococcus species in peritonitis is associated with worse outcomes 1, 2
• In experimental peritonitis models, high concentrations of E. faecalis enhanced the severity of infection by increasing the counts of other pathogens like E. coli and B. fragilis 6
• Enterococcus plays an important role in bacterial synergy mechanisms in peritonitis, potentially making infections more severe 6

Pitfalls to Avoid

• Failing to cover for Enterococcus in healthcare-associated infections can lead to treatment failure and worse outcomes 1
• Prolonged antibiotic therapy (>10 days) increases the risk of enterococcal colonization and potential superinfection with resistant strains 3
• Using antibiotics that lack enterococcal coverage (such as cephalosporins alone) in high-risk patients may lead to treatment failure 2
• Not adjusting therapy when cultures reveal Enterococcus species, especially in patients with risk factors 1

In conclusion, for patients with feculent peritonitis, especially in healthcare-associated settings or with the risk factors mentioned above, empiric coverage for Enterococcus faecalis is strongly recommended to improve clinical outcomes and reduce mortality.