Imipenem-resistance among multi-drug resistant clinical strains in urinary infections from Kolkata.

Imipenem (N-formimidiyl thienamycin), a carbapenem, is a semisynthetic derivative of thienamycin produced by Streptomyces cattleya. It exerts its bactericidal action by inhibiting cell wall synthesis in aerobic and anaerobic Gram-positive and Gram-negative bacteria. Imipenem shows strong affinity for penicillin binding protein of Escherichia coli and selected strains of Pseudomonas aeruginosa resulting in rapid lysis and cell death without filament formation. Bacterial resistance to imipenem can occur due to production of carbapenemase or metallobeta lactamase capable of hydrolyzing the carbapenem nucleus and also able to alter the porin channels in the bacterial cell wall, thereby reducing the permeability of the drug. Carbapenems have been used in clinical settings as a last resort for their broadspectrum antibacterial activity and stability against various beta-lactamases produced by Gram-negative bacteria including extended-spectrum betalactamases (ESBLs). Imipenem (IPM) was approved for clinical use in 1987 in Japan, followed by panipenem and meropenem in 1993 and 1995, respectively. Carbapenem resistant strains emerged in Japan by 1999.