In vitro activity of ertapenem: review of recent studies


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Abstract

Ertapenem is a long-acting, 1β-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. MIC90s for most species of Enterobacteriaceae were <1 mg/L, significantly lower than those of imipenem. MIC90s for most Bacteroides fragilis group isolates ranged from 1 to 4 mg/L, and MIC90s 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-β-lactamase enzymes, porin protein defects and efflux pumps in Gram-negative organisms.

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