In vitro activity of meropenem (SM-7338), imipenem, and five other antibiotics against anaerobic clinical isolates

The in vitro susceptibility of 513 recent anaerobic clinical isolates was evaluated against meropenem (SM-7338), a new carbapenem, and six other antibiotics. Virtually all Gram-positive and Gram-negative anaerobic bacteria tested were susceptible to meropenem (defined as MICs less than or equal to 8 micrograms/ml) with 99.8% of the isolates inhibited by less than or equal to 4 micrograms/ml. The activity of meropenem was comparable to imipenem for most clinical isolates. Minor differences were observed for Clostridium and Veillonella (meropenem more active) and other Gram-positive bacilli (imipenem more active). Meropenem inhibited all anaerobes resistant to clindamycin and metronidazole. Bactericidal tests performed with meropenem demonstrated killing activity against all isolates except Clostridium and Lactobacillus.