Meropenem is a carbapenem antibiotic. It is active against clinical isolates of Gram-positive and Gram-negative bacteria in vitro, including S. pneumoniae, H. influenzae, N. gonorrhoeae, E. coli, P. aeruginosa, C. difficile, and methicillin-susceptible and -resistant S. aureus (MICs = ≤0.008-8 μg/ml). It is protective against S. aureus, S. pneumoniae, E. coli, S. marcescens, P. mirabilis, and P. aeruginosa infections in mice with 50% protective dose (PD50) values of 0.13, 0.01, 0.04, 0.07, 0.84, and 0.46 mg/kg, respectively. Formulations containing meropenem have been used in the treatment of a variety of bacterial infections.