Ceftolozane/Tazobactam and Ceftazidime/Avibactam for the Treatment of Complicated and Nosocomial Pseudomonas aeruginosa Infections

Increasingly difficult-to-treat (DTR) Pseudomonas aeruginosa ( P. aeruginosa) remains a common cause of serious infections. Newer beta-lactam agents such as ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (C/A) offer extended antimicrobial spectrums preferred for addressing this problem. The objective of this systematic review is to evaluate the efficacy and safety of ceftolozane/tazobactam and ceftazidime/avibactam compared to best available therapy, primarily carbapenems, for the treatment of either complicated urinary tract infections (cUTIs), complicated intra-abdominal infections (cIAIs), or nosocomial pneumonia (NP) caused by P. aeruginosa . A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards on PubMed, Embase, and Cochrane Central for all available data through June 2025. Randomized controlled trials (RCTs) with participants 18 years of age or above that compared the efficacy and safety of either C/A or C/T for cUTIs, cIAIs, or NP caused by P. aeruginosa were included. A total of 439 studies were screened, and 8 RCTs were included. Treatment with C/T or C/A showed similar results when compared primarily to carbapenems for cUTIs, cIAIs, or NP caused by P. aeruginosa . Such results encompassed clinical response or cure, microbiological response or eradication, and safety outcome measures. While our findings demonstrate efficacious similarity comparing C/T or C/A to the best available therapy, current in vitro and head-to-head observational data show potential benefit in utilizing C/T over C/A. Additional robust randomized trials are needed to validate definitive therapy.