cefotaxime + imipenem + cilastatin + piperacillin + tazobactam

This is a combination of five antibiotics and antibiotic adjuncts, each with distinct mechanisms of action.

• Cefotaxime is a third-generation cephalosporin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.
• Imipenem is a carbapenem antibiotic that also inhibits bacterial cell wall synthesis via PBPs; it has broad-spectrum activity against Gram-positive and Gram-negative bacteria.
• Cilastatin is not an antibiotic but an inhibitor of renal dehydropeptidase I, used in combination with imipenem to prevent its degradation in the kidneys, thereby increasing imipenem's efficacy.
• Piperacillin is an extended-spectrum ureidopenicillin that targets PBPs for bactericidal activity, especially against Pseudomonas aeruginosa and other Gram-negative organisms.
• Tazobactam is a β-lactamase inhibitor combined with piperacillin to protect it from enzymatic breakdown by β-lactamases produced by resistant bacteria.

This combination would theoretically provide extremely broad antibacterial coverage—including many multidrug-resistant organisms—by combining multiple classes of β-lactams (cephalosporin, carbapenem, penicillin) plus two β-lactamase inhibitors (cilastatin as adjunct for imipenem; tazobactam for piperacillin). However, there are no known approved or marketed products containing all five agents together; such combinations are typically used separately or in pairs (e.g., imipenem-cilastatin or piperacillin-tazobactam).