metronidazole + tazobactam + ceftolozane

This is a combination regimen of three agents—metronidazole, tazobactam, and ceftolozane—used primarily for the treatment of complicated intra-abdominal infections (cIAI). Ceftolozane is a novel cephalosporin antibiotic with potent activity against gram-negative bacteria, including multidrug-resistant Pseudomonas aeruginosa. Tazobactam is a β-lactamase inhibitor that extends the spectrum of ceftolozane by inhibiting bacterial enzymes that degrade β-lactams. Metronidazole is an antianaerobic agent effective against anaerobic bacteria commonly found in intra-abdominal infections. The combination targets both aerobic and anaerobic pathogens, providing broad-spectrum coverage for severe abdominal infections. This regimen has demonstrated noninferiority to meropenem in clinical trials for cIAI and is approved for use in adults and pediatric patients.