Which one of the following statements about imipenem is MOST accurate? A: The drug has a narrow spectrum of antibacterial action B: It is used in fixed combination with sulbactam C: Imipenem is highly susceptible to b-lactamases produced by Enterobacter species D: In renal dysfunction, dosage reductions are necessary to avoid seizures E: Imipenem is active against methicillin-resistant Staphylococci