Ertapenem Coverage of Corynebacterium
Ertapenem does NOT provide reliable coverage against Corynebacterium species and should not be used when targeting these organisms. 1, 2, 3
Spectrum Limitations of Ertapenem
Ertapenem is a Group 1 carbapenem with a narrower antimicrobial spectrum compared to other carbapenems (imipenem, meropenem, doripenem). 2, 4
Key organisms NOT covered by ertapenem include:
- Pseudomonas aeruginosa 1, 2, 3
- Enterococcus species 2, 3, 4
- Acinetobacter species 1, 3
- Methicillin-resistant Staphylococcus aureus 3, 4
- Corynebacterium species (by extension of its limited Gram-positive coverage) 3, 4
Ertapenem's Appropriate Spectrum
Ertapenem demonstrates excellent activity against:
- ESBL-producing Enterobacteriaceae 1, 2, 3
- Most Gram-negative aerobic bacteria (excluding Pseudomonas) 3, 5
- Anaerobic bacteria including Bacteroides fragilis 3, 5
- Streptococcus pneumoniae 3, 5
- Methicillin-susceptible Staphylococcus aureus 3
Clinical Implications
Ertapenem is designed for community-acquired polymicrobial infections, not for targeting Gram-positive organisms like Corynebacterium. 4, 6, 7
The restricted Gram-positive activity of ertapenem compared to imipenem and meropenem makes it unsuitable for nosocomial pathogens and organisms requiring broader Gram-positive coverage. 3, 4
Alternative Carbapenem Selection
If carbapenem coverage is needed for Corynebacterium:
- Imipenem-cilastatin or meropenem should be considered instead, as they have broader Gram-positive activity 1, 2, 4
- These Group 2 carbapenems maintain activity against a wider range of Gram-positive organisms 2, 4
Common Pitfall
A critical error is assuming all carbapenems have identical spectrums—ertapenem's once-daily dosing convenience comes at the cost of narrower coverage, specifically excluding enterococci, Pseudomonas, and having limited activity against other Gram-positive organisms including Corynebacterium. 4, 6, 7