What bacteria are covered by carbapenems (antibiotics)?

From the Guidelines

Carbapenems are broad-spectrum antibiotics that cover a wide range of bacteria, including many gram-positive, gram-negative, and anaerobic organisms, such as Enterobacteriaceae (e.g., E. coli, Klebsiella, and Enterobacter), with the exception of methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium. The spectrum of activity of carbapenems includes:

• Gram-positive organisms like Streptococcus species and methicillin-sensitive Staphylococcus aureus (MSSA) 1
• Gram-negative organisms including Pseudomonas aeruginosa (for some carbapenems like imipenem/cilastatin, meropenem, and doripenem, but not ertapenem) and Acinetobacter species 1
• Anaerobes like Bacteroides fragilis 1 However, carbapenems are not effective against carbapenem-resistant organisms, such as some strains of Klebsiella pneumoniae carbapenemase (KPC) producers or organisms with metallo-beta-lactamases 1. Carbapenems, including meropenem, imipenem-cilastatin, ertapenem, and doripenem, work by binding to penicillin-binding proteins to inhibit bacterial cell wall synthesis and are resistant to most beta-lactamases that typically degrade other beta-lactam antibiotics 1. Given the rising concern of antimicrobial resistance, the use of carbapenems should be limited to preserve the activity of this class of antibiotics, especially for multidrug-resistant infections caused by Enterobacteriaceae 1.

From the FDA Drug Label

Meropenem has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections Gram-positive bacteria Enterococcus faecalis (vancomycin-susceptible isolates only) Staphylococcus aureus (methicillin-susceptible isolates only) Streptococcus agalactiae Streptococcus pneumoniae (penicillin-susceptible isolates only) Streptococcus pyogenes Viridans group streptococci Gram-negative bacteria Escherichia coli Haemophilus influenzae Klebsiella pneumoniae Neisseria meningitidis Proteus mirabilis Pseudomonas aeruginosa Anaerobic bacteria Bacteroides fragilis Bacteroides thetaiotaomicron Peptostreptococcus species

Carbapenems, such as meropenem, cover a wide range of bacteria, including:

• Gram-positive bacteria:
  • Enterococcus faecalis (vancomycin-susceptible isolates only)
  • Staphylococcus aureus (methicillin-susceptible isolates only)
  • Streptococcus agalactiae
  • Streptococcus pneumoniae (penicillin-susceptible isolates only)
  • Streptococcus pyogenes
  • Viridans group streptococci
• Gram-negative bacteria:
  • Escherichia coli
  • Haemophilus influenzae
  • Klebsiella pneumoniae
  • Neisseria meningitidis
  • Proteus mirabilis
  • Pseudomonas aeruginosa
• Anaerobic bacteria:
  • Bacteroides fragilis
  • Bacteroides thetaiotaomicron
  • Peptostreptococcus species 2

From the Research

Bacteria Covered by Carbapenems

Carbapenems are a class of broad-spectrum beta-lactam antibiotics that cover a wide range of bacterial pathogens, including:

• Streptococci
• Methicillin-sensitive staphylococci
• Neisseria
• Haemophilus
• Anaerobes
• Aerobic gram-negative nosocomial pathogens, including Pseudomonas 3
• Enterobacteriaceae, such as Escherichia coli 4
• Staphylococci, Streptococci, and anaerobes 4

Exceptions and Resistance

However, there are some exceptions and resistant strains, including:

• Stenotrophomonas maltophilia, which is typically resistant to both imipenem and meropenem 3
• X. maltophilia, E. faecium, and some strains of methicillin-resistant staphylococci and penicillin-resistant pneumococci 5
• Pseudomonas aeruginosa, which may develop resistance to imipenem and meropenem during treatment 3, 6
• Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, which may be co-resistant to carbapenems, aminoglycosides, polymyxins, and tigecycline 7

Spectrum of Activity

The spectrum of activity of carbapenems varies among different species, with:

• Imipenem having greater in vitro activity against aerobic gram-positive cocci than meropenem 3
• Meropenem having greater in vitro activity against aerobic gram-negative bacilli than imipenem 3
• Meropenem displaying lower MICs against Enterobacteriaceae, Escherichia coli, and Pseudomonas aeruginosa compared to imipenem 4