Imipenem is one of the semisynthetic thienamycins with antibacterial activity against gram-negative and gram-positive aerobic and anaerobic bacteria, which is stable to many beta-lactamases and shows a long half-life because of binding to plasma proteins [1].
Penicillin-binding proteins (PBPs) are a kind of membrane proteins, widely existing on the surface of bacteria, which is the main target site of beta-lactam antibiotics.
In E. coli and selected strains of P. aeruginosa, imipenem has shown to have the highest affinity to PBP-2, PBP-1a, and PBP-1b [2]. The inhibition of PBPs reduces the number of peptidoglycan polymer in the bacterial cell, thus prevent the forming of the bacterial cell wall and lead to cell death [3].
Reference:
[1]. Zhanel G G, Wiebe R, Dilay L, et al. Comparative review of the carbapenems [J]. Drugs, 2007, 67(7): 1027-52.
[2]. Nicolau D P. Carbapenems: a potent class of antibiotics [J]. Expert Opin Pharmacother. 2008, 9(1): 23-37.
[3]. Brunton L L, Hilal-Dandan R, Knollmann B C. eds (2018). Goodman & Gilman's: The Pharmacological Basis of Therapeutics (13th ed.). McGraw-Hill Education.