What group of bacteria is covered by Meropenem (carbapenem antibiotic)?

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Meropenem Antibiotic Coverage

Meropenem is a carbapenem antibiotic that provides broad-spectrum coverage against Gram-negative bacteria, Gram-positive bacteria (excluding MRSA), and anaerobic organisms. 1

Gram-Negative Coverage

Meropenem demonstrates particularly robust activity against Gram-negative pathogens, which represents its primary clinical strength:

  • Enterobacteriaceae: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter species, Citrobacter species, and Serratia marcescens 1, 2
  • Non-fermentative Gram-negative bacilli: Pseudomonas aeruginosa and Acinetobacter species 2, 3
  • Other Gram-negatives: Haemophilus influenzae and Neisseria meningitidis 1, 3

Meropenem is specifically recommended for infections caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and AmpC-hyperproducing organisms (such as Enterobacter, Citrobacter, and Serratia), where other β-lactams frequently fail. 4, 5, 2

Gram-Positive Coverage

Meropenem covers most clinically relevant Gram-positive organisms, with important exceptions:

  • Streptococci: Streptococcus pneumoniae (penicillin-susceptible), Streptococcus pyogenes, Streptococcus agalactiae, and viridans group streptococci 1, 3
  • Staphylococci: Staphylococcus aureus (methicillin-susceptible isolates only) 1
  • Enterococci: Enterococcus faecalis (vancomycin-susceptible isolates only) 1, 3

Critical limitation: Meropenem has NO activity against methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant Staphylococcus epidermidis (MRSE), requiring addition of vancomycin when these pathogens are suspected. 5

Anaerobic Coverage

Meropenem provides comprehensive anaerobic coverage, eliminating the need for metronidazole when used as monotherapy for polymicrobial infections. 5

  • Anaerobes covered: Bacteroides fragilis, B. thetaiotaomicron, and Peptostreptococcus species 1, 2

This broad anaerobic activity makes meropenem particularly valuable for intra-abdominal infections and complicated skin/soft tissue infections where mixed aerobic-anaerobic flora is expected. 5

Resistance Considerations

Important caveat: Stenotrophomonas maltophilia is typically resistant to meropenem and requires alternative agents. 3

For carbapenem-resistant organisms producing metallo-β-lactamases or KPC carbapenemases, newer agents like meropenem-vaborbactam, cefiderocol, or combination therapies are required. 4, 5

Comparative Activity Profile

Compared to imipenem, meropenem demonstrates greater activity against Gram-negative pathogens but somewhat less activity against Gram-positive organisms. 6, 3 This makes meropenem particularly well-suited for nosocomial infections where multidrug-resistant Gram-negative bacteria predominate. 7

References

4
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

5
Guideline

Meropenem Effectiveness Against Gram-Negative Rods

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

6
Research

Update on the efficacy and tolerability of meropenem in the treatment of serious bacterial infections.

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2008

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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