Ertapenem is a long-acting, 1beta-methyl parenteral Group 1
carbapenem antibiotic that has a broad antibacterial spectrum and once-a-day dosing supported by clinical studies.
Ertapenem is active against both Gram-positive and Gram-negative bacteria, including Enterobacteriaceae, Streptococcus pneumoniae and most species of anaerobic bacteria. Isolates from a variety of
infections (intra-abdominal infections, skin/
soft-tissue infections, community-acquired
pneumonia,
pelvic infections and
urinary tract infections) are inhibited by
ertapenem. It has restricted activity against nosocomial pathogens such as Pseudomonas aeruginosa, Acinetobacter species, methicillin-resistant staphylococci and enterococci.
Ertapenem has potent activity against the majority of anaerobic isolates from
intra-abdominal infections, and against most of the aerobes isolated from these
infections, with the exceptions of the nosocomial pathogens mentioned above. MIC(90)s for most species of Enterobacteriaceae were <1 mg/L, significantly lower than those of
imipenem. MIC(90)s for most Bacteroides fragilis group isolates ranged from 1 to 4 mg/L, and MIC(90)s were species specific for Clostridium, ranging from 0.06 mg/L for Clostridium perfringens to 4 mg/L for Clostridium clostridioforme.
Ertapenem was equivalent to or better than
piperacillin-tazobactam in activity against most anaerobic species isolated from these
infections, and was more potent than
piperacillin-tazobactam and
ceftriaxone against the most common skin pathogens (e.g.
methicillin-susceptible Staphylococcus aureus).
Ertapenem was highly active against most of the pathogens isolated from patients with community-acquired
pneumonia, except for isolates of methicillin-resistant S. aureus (which are infrequent causes of
community-acquired infection); these isolates were also resistant to
ceftriaxone. Resistance to
ertapenem is most commonly attributable to a variety of mechanisms including alterations in
penicillin-binding proteins in Gram-positive organisms, and combinations of potent metallo-
beta-lactamase enzymes,
porin protein defects and efflux pumps in Gram-negative organisms.