Antibacterial Activity of Imipenem: The First Thienamycin Antibiotic

Imipenem (N-formimidoyl thienamycin) is the first representative of a new class of β-lactam antibiotics - the carbapenems. Imipenem has an unusually broad spectrum, high potency, and no cross-resistance with other β-lactam antibiotics. Susceptible gram-negative species include Pseudomonas aeruginosa, Serratia, and Enterobacter. Activity is high against Staphylococcus aureus, most group D streptococci, and Staphylococcus epidermidis but is variable against methicillin-resistant S. aureus. Imipenem is more active against Bacteroides than are other β-lactam agents, chloramphenicol, metronidazole, and clindamycin. The minimal inhibitory concentrations (MICs) for 98% of 30,655 isolates - excluding those of the three resistant species (Pseudomonas maltophilia, Pseudomonas cepacia, and Streptococcus faecium) - were