The growth-inhibitory properties of meropenem against anaerobes of clinical importance.

The in-vitro activity of meropenem against anaerobic bacteria was assessed by an agar dilution procedure. MICs were measured for 449 clinical isolates and reference strains. Meropenem showed excellent activity against both Gram-negative anaerobes, including Bacteroides fragilis (MIC90 0.25 mg/l), and Gram-positive anaerobes. The MIC90 for Clostridium perfringens was 0.01 mg/l. Meropenem had comparable activity to imipenem against Gram-negative anaerobes but was more active than imipenem against clostridia, including C. difficile (MIC90 2 mg/l compared with 8 mg/l). Meropenem was more active against anaerobes than was cefoxitin, metronidazole or clindamycin.