Comparison of antimicrobial activity between ceftolozane-tazobactam and ceftazidime-avibactam against multidrug-resistant isolates of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa

Abstract

Objective: This study compared the activity of ceftolozane-tazobactam and ceftazidime-avibactam against 120 bacterial strains, including extended-spectrum beta-lactamase (ESBL) producers, carbapenem-resistant Enterobacteriaceae (CRE), and Pseudomonas aeruginosa, isolated from patients admitted to Cleveland Clinic Abu Dhabi, United Arab Emirates.

Methods: In vitro susceptibility was tested using the Etest strip minimum inhibitory concentration (MIC) method, and PCR was used to characterize the carbapenemase enzymes produced by CRE strains.

Results: All 29 ESBL isolates were susceptible to ceftazidime-avibactam (MIC₅₀ 0.125μg/ml), whereas all but one were susceptible to ceftolozane-tazobactam (MIC₅₀ 0.38μg/ml). Twenty-seven (45%) CRE isolates were susceptible to ceftazidime-avibactam (MIC₅₀ ≥256μg/ml), whereas only six (10%) isolates were susceptible to ceftolozane-tazobactam (MIC₅₀ ≥256μg/ml). Very few NDM-1 isolates were susceptible to ceftazidime-avibactam, whereas the majority of OXA-48 isolates were susceptible. Twenty-nine (94%) P. aeruginosa isolates were susceptible to ceftazidime-avibactam (MIC₅₀ 1.5μg/ml), whereas 30 (97%) isolates were susceptible to ceftolozane-tazobactam (MIC₅₀ 0.75μg/ml).

Conclusions: Ceftolozane-tazobactam and ceftazidime-avibactam showed comparable activity against ESBL and P. aeruginosa, with ceftazidime-avibactam having lower MICs against ESBL isolates and ceftolozane-tazobactam having lower MICs against P. aeruginosa. Ceftazidime-avibactam showed better activity against all CRE isolates except for those carrying the NDM-1 enzyme.

Keywords: Ceftazidime–avibactam; Ceftolozane–tazobactam; Gram-negative bacteria; Multidrug resistance; carbapenem-resistant Enterobacteriaceae (CRE).