cefotaxime + colistin + nystatin + tobramycin

This is a combination of four antimicrobial agents—cefotaxime, colistin, nystatin, and tobramycin—used primarily in protocols for selective digestive decontamination (SDD) in intensive care settings. - **Cefotaxime** is a third-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to bactericidal activity against a broad spectrum of Gram-positive and Gram-negative bacteria[1]. - **Colistin** (also known as polymyxin E) is a polymyxin antibiotic that disrupts the bacterial cell membrane of Gram-negative organisms by interacting with lipopolysaccharides and phospholipids[6][8]. - **Nystatin** is an antifungal agent that binds to ergosterol in fungal cell membranes, creating pores and causing leakage of cellular contents. - **Tobramycin** is an aminoglycoside antibiotic that inhibits protein synthesis by binding to the 30S ribosomal subunit in susceptible bacteria[6][8]. This combination aims to eradicate potentially pathogenic aerobic Gram-negative bacteria, *Staphylococcus aureus*, and yeasts from the digestive tract while sparing anaerobic flora. It is used prophylactically in critically ill patients (especially those on mechanical ventilation) to prevent ICU-acquired infections such as ventilator-associated pneumonia or sepsis[6][8].