In-vitro and in-vivo antibacterial activity of imipenem against clinical isolates of bacteria.

Imipenem, a derivative of thienamycin, a carbapenem antibiotic, has a broad spectrum of activity against aerobic (Gram-positive and Gram-negative) and anaerobic bacteria. It is quite stable to all tested beta-lactamases produced by various species of bacteria isolated from clinical specimens, whether plasmid or chromosomally mediated. One exception is its hydrolysis by the beta-lactamase produced by Pseudomonas maltophilia which is thus usually resistant to imipenem. Imipenem was found to be hydrolysed by renal dehydropeptidase-I residing on the luminal surface of the renal tubular epithelium. A dehydropeptidase-I inhibitor, cilastatin (MK-0791) was developed with specific inhibitory activity toward the renal dehydropeptidase-I and showed detectable effects in humans.