colistin + meropenem + tigecycline

This is a combination therapy consisting of three antibiotics—colistin, meropenem, and tigecycline—used primarily for the treatment of infections caused by multidrug-resistant Gram-negative bacteria, including carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Klebsiella pneumoniae (CRKP), and extensively drug-resistant Acinetobacter baumannii (XDR-AB).

• Colistin is a polymyxin antibiotic that disrupts the bacterial outer membrane by binding to lipopolysaccharides and phospholipids, leading to cell death.
• Meropenem is a broad-spectrum carbapenem β-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins.
• Tigecycline is a glycylcycline antibiotic that inhibits protein synthesis by binding to the 30S ribosomal subunit.

The triple combination has been studied in vitro and in animal models for its bactericidal activity against highly resistant strains where monotherapies or dual therapies may be insufficient. The rationale for this combination lies in their complementary mechanisms of action and potential synergistic effects against pathogens with complex resistance profiles.