Does meropenem cover Enterococcus?

Meropenem Coverage of Enterococcus

Meropenem does not adequately cover Enterococcus faecalis and has no reliable activity against Enterococcus faecium, requiring additional antimicrobial coverage when treating infections where enterococci are suspected or confirmed pathogens. 1, 2, 3

Spectrum of Activity Against Enterococci

Meropenem demonstrates the following activity against enterococci:

• Enterococcus faecalis: Only moderate activity with mean MIC of 5 mg/L 3
• Enterococcus faecium: Poor activity with mean MIC of 11.6 mg/L, considered uniformly resistant 4, 3
• Comparative activity: Less active against enterococci than imipenem, though both carbapenems have limited enterococcal coverage 5

Clinical Implications

When Treating Intra-abdominal Infections

• Community-acquired infections: Empiric coverage of Enterococcus is not necessary 1
• Healthcare-associated infections: Antimicrobial therapy for enterococci should be given when enterococci are recovered 1
• High-risk patients: Empiric anti-enterococcal therapy is recommended for:
  • Patients with healthcare-associated infections
  • Postoperative infections
  • Prior cephalosporin exposure
  • Immunocompromised patients
  • Patients with valvular heart disease or prosthetic intravascular materials 1

Recommended Regimens When Enterococcal Coverage Is Needed

When treating nosocomial postoperative infections where enterococci are likely pathogens:

• Meropenem alone is insufficient for enterococcal coverage 1, 4
• Additional coverage (e.g., vancomycin) may be needed for adequate enterococcal coverage 1
• Alternative combination: Meropenem plus ceftaroline has shown activity against E. faecalis in in vitro studies 6

Practical Considerations

When to Consider Additional Enterococcal Coverage with Meropenem

1. Nosocomial infections: Particularly postoperative infections 1
2. Severe healthcare-associated intra-abdominal infections: Especially in immunocompromised patients 1
3. Patients with prior cephalosporin exposure: Higher risk of enterococcal infections 1
4. Positive cultures: When enterococci are recovered from clinical specimens 1

Pitfalls to Avoid

• Relying on meropenem alone for enterococcal coverage, especially for E. faecium which is uniformly resistant 4
• Overlooking the need for enterococcal coverage in healthcare-associated infections 1
• Unnecessary enterococcal coverage in community-acquired infections where it's not typically needed 1

Alternative Regimens with Better Enterococcal Coverage

For infections requiring enterococcal coverage, consider:

• Ampicillin plus ceftriaxone (standard of care for E. faecalis infections) 6
• Piperacillin-tazobactam (better enterococcal coverage than meropenem) 1
• Addition of vancomycin to meropenem when enterococcal coverage is needed 1

In summary, while meropenem is an excellent broad-spectrum antibiotic for many serious infections, it should not be relied upon for enterococcal coverage, particularly for E. faecium. Additional targeted therapy is required when enterococcal infection is suspected or confirmed.