What is the antimicrobial coverage of Merrem (Meropenem)?

Antimicrobial Coverage of Meropenem (Merrem)

Meropenem provides broad-spectrum coverage against gram-positive, gram-negative, and anaerobic bacteria, making it an effective option for serious infections including complicated intra-abdominal infections, nosocomial pneumonia, bacterial meningitis, and healthcare-associated infections. 1

Spectrum of Activity

Gram-Positive Coverage

• Susceptible organisms include:
  • Streptococcus pneumoniae (penicillin-susceptible isolates only)
  • Streptococcus pyogenes
  • Streptococcus agalactiae
  • Viridans group streptococci
  • Staphylococcus aureus (methicillin-susceptible isolates only)
  • Enterococcus faecalis (vancomycin-susceptible isolates only) 1

Gram-Negative Coverage

• Highly active against:
  • Escherichia coli
  • Klebsiella pneumoniae
  • Pseudomonas aeruginosa
  • Haemophilus influenzae
  • Neisseria meningitidis
  • Proteus mirabilis 1
  • Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae 2
  • AmpC-producing Enterobacteriaceae 2

Anaerobic Coverage

• Effective against:
  • Bacteroides fragilis
  • Bacteroides thetaiotaomicron
  • Peptostreptococcus species 1
  • Clostridium species 1

Clinical Applications

Intra-abdominal Infections

• Recommended for higher-risk patients with complicated intra-abdominal infections 3
• Particularly valuable for nosocomial infections requiring coverage against P. aeruginosa, Enterobacter spp., and Proteus spp. 3

Skin and Soft Tissue Infections

• Indicated for complicated skin and soft tissue infections 2
• Recommended for necrotizing soft tissue infections, particularly in healthcare-associated cases 3

Meningitis

• One of the few carbapenems approved for bacterial meningitis due to its low seizure potential 2
• Recommended as an alternative to cefotaxime or ceftriaxone for bacterial meningitis 3
• Particularly valuable for meningitis caused by gram-negative bacilli that produce extended-spectrum β-lactamases 3

Febrile Neutropenia

• Recommended as monotherapy for high-risk patients with febrile neutropenia 3
• More effective than ceftazidime or piperacillin/tazobactam in febrile neutropenia 2

Advantages Over Other Antimicrobials

• Compared to imipenem:

  • Lower seizure potential, making it safer for CNS infections 4
  • More active against most gram-negative pathogens, including Pseudomonas aeruginosa 5
  • Can be administered as an IV bolus or infusion 2

• Compared to cephalosporins:

  • More effective than ceftazidime-based regimens for nosocomial lower respiratory tract infections 5
  • Stable against chromosomal and extended-spectrum beta-lactamases 6

Limitations

• Not effective against:

  • Methicillin-resistant Staphylococcus aureus (MRSA)
  • Methicillin-resistant Staphylococcus epidermidis (MRSE)
  • Most Enterococcus species 1

• Resistance mechanisms:

  • Decreased outer membrane permeability
  • Reduced affinity of target PBPs
  • Increased expression of efflux pumps
  • Production of carbapenemases and metallo-β-lactamases 1

Clinical Pearls

• Meropenem acts synergistically with aminoglycosides against some isolates of Pseudomonas aeruginosa 1
• For serious infections, the typical dosage is 1 gram IV every 8 hours 1
• Dose adjustment is required in patients with renal impairment 1
• Should be reserved for serious infections to prevent development of resistance
• Consider using ertapenem instead when Pseudomonas coverage is not needed, as this promotes antimicrobial stewardship 7

Meropenem remains an important option for empirical treatment of serious bacterial infections in hospitalized patients, particularly when broad-spectrum coverage including Pseudomonas aeruginosa is required.