Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis




Pharmaceutical Sciences

First Advisor

Dr. David Burgess


Pseudomonas aeruginosa causes severe healthcare-associated infections. Forty-eight extensively drug-resistant (XDR)-P. aeruginosa isolates were selected from 287 isolates collected for evaluation based on clinical susceptibility data. In vitro activity of commonly utilized antimicrobials (i.e. antipseudomonal beta-lactams, aminoglycosides, fluoroquinolones, and polymyxins) plus ceftolozane-tazobactam, ceftazidime-avibactam, and aztreonam-avibactam against XDR-P. aeruginosa were determined. The mechanism of resistance profile was determined through phenotypic expression analysis. Overall, polymyxin B and colistin were 100% susceptible. Apart from the polymyxins, ceftolozane-tazobactam had the highest susceptibility (94%) followed by ceftazidime-avibactam (90%) and amikacin (83%). Ceftolozane-tazobactam activity was not significantly different from ceftazidime-avibactam (p=0.6831). Only 40% of isolates were susceptible to aztreonam-avibactam. All other agents demonstrated P. aeruginosa at our institution, in vitro analysis proposes superiority of ceftolozane-tazobactam; however, until further in vitro and in vivo validation both agents are reasonable options.

Digital Object Identifier (DOI)