polymyxin + ciprofloxacin + amphotericin

This is a combination of three antimicrobial agents—polymyxin (typically polymyxin B or colistin), ciprofloxacin, and amphotericin (usually amphotericin B)—used together for their synergistic effects against severe infections, particularly those caused by multidrug-resistant organisms. Polymyxins are cationic polypeptide antibiotics that disrupt the outer membrane of Gram-negative bacteria by binding to lipid A in lipopolysaccharides, leading to increased membrane permeability and cell death[6][8]. Ciprofloxacin is a fluoroquinolone antibiotic that inhibits bacterial DNA gyrase and topoisomerase IV, enzymes essential for DNA replication and transcription. Amphotericin B is an antifungal polyene that binds irreversibly to ergosterol in fungal cell membranes, forming pores that increase membrane permeability and cause leakage of intracellular contents[3]. This combination may be considered in complex clinical scenarios such as respiratory infections with multidrug-resistant Gram-negative bacteria or mixed bacterial-fungal infections.