colistin + polymyxin B + sulbactam

A combination antimicrobial therapy composed of **colistin**, **polymyxin B**, and **sulbactam**. This regimen brings together two polymyxin antibiotics (colistin and polymyxin B) and a beta-lactamase inhibitor (sulbactam) to enhance antibacterial activity, particularly against multidrug-resistant Gram-negative bacteria such as *Acinetobacter baumannii*. - **Colistin** (also known as polymyxin E) and **polymyxin B** are cationic polypeptide antibiotics that interact with the lipopolysaccharide (LPS) in the bacterial outer membrane, destabilizing membrane integrity, increasing permeability, and ultimately leading to cell death. Both also neutralize endotoxins and inhibit inflammatory cytokine production[4][6][8]. - **Sulbactam** is a beta-lactamase inhibitor with intrinsic activity against certain *Acinetobacter* strains, acting primarily through irreversible inhibition of beta-lactamase enzymes, thereby restoring susceptibility to beta-lactam antibiotics and exerting direct bactericidal action against some bacteria[8]. This triple combination aims to provide synergistic effects for severe or resistant infections, especially where monotherapies or dual combinations are ineffective, as shown in both preclinical and clinical studies for polymyxin-resistant, carbapenem-resistant *A. baumannii*[1][5][7].