From the Research
Ertapenem does not provide reliable coverage against Enterococcus faecalis. This carbapenem antibiotic has poor activity against enterococci, including E. faecalis, and should not be used if enterococcal coverage is needed 1. The reason for ertapenem's poor activity against enterococci relates to its molecular structure and binding affinity for penicillin-binding proteins in enterococcal cell walls, which differs from other carbapenems like imipenem and meropenem.
Some studies have shown that ertapenem has some in vitro activity against Enterococcus faecalis, but this activity is not reliable enough to make it a first-line choice for treating enterococcal infections 2. In fact, a study published in 2019 found that inefficient antimicrobial therapy, including the use of ertapenem, was associated with a higher risk of unfavorable outcomes in patients with enterococcal bacteraemia 3.
If treating an infection where E. faecalis is confirmed or suspected, alternative antibiotics such as:
- ampicillin (2g IV every 4-6 hours)
- amoxicillin (500mg-875mg orally every 8-12 hours)
- vancomycin (15-20mg/kg IV every 8-12 hours) would be more appropriate choices. For serious enterococcal infections, combination therapy with an aminoglycoside (such as gentamicin) may be necessary for synergistic bactericidal activity.
It's worth noting that other carbapenems, such as imipenem and meropenem, also have limited activity against enterococci and should not be used as first-line agents for enterococcal infections. The choice of antibiotic should always be guided by the results of susceptibility testing and the severity of the infection.