Antimicrobial activity of ceftolozane-tazobactam against multidrug-resistant and extensively drug-resistant Pseudomonas aeruginosa clinical isolates from a Spanish hospital

OBJECTIVES: Our objective was to evaluate the in vitro activity of ceftolozane-tazobactam against multidrug resistant (MDR) and extensively drug-resistant (XDR) non metallo-β-lactamase producing Pseudomonas aeruginosa clinical isolates at Hospital Universitario Miguel Servet (Zaragoza, Spain) from February 2016 to October 2017. MATERIAL AND METHODS: We evaluated the in vitro activity of ceftolozane-tazobactam and other antipseudomonal antibiotics against 12 MDR and 117 XDR non metallo-β-lactamase producing P. aeruginosa isolates. Ceftolozane-tazobactam minimal inhibitory concentrations (MICs) were determined by MIC gradient diffusion test strip. RESULTS: Among the 129 MDR/XDR isolates included, 119 (92.2%) were susceptible to ceftolozane-tazobactam, and ten (7.8%) were resistant. MIC(50) was 2 mg/L, and MIC(90) 4 mg/L. Ceftolozane-tazobactam was the second most active antibiotic after colistin, overtaking amikacin. CONCLUSIONS: Ceftolozane-tazobactam is a valuable treatment option for MDR and XDR P. aeruginosa infections in our setting.