Bacteriophage Preparations and Antibiotic Combinations: In vitro Activity Against Extensively Drug-Resistant Isolates of Pseudomonas aeruginosa ST235

Abstract

The activity of 11 antibiotics combinations and 4 commercially available preparations for phagotherapy in regard to metallo-beta-lactamase (MBL) producing Pseudomonas aeruginosa clinical isolates of sequence type 235 (ST 235) belonging to the clonal complex (CC 235) is studied. High levels of drug resistance of MBL-producing Pseudomonas aeruginosa isolates with multiple excess of threshold PC/PD-concentrations for beta-lactams, aminoglycosides and fluorquinolones and preserved sensitivity only to polymyxins are revealed. Synergetic and additive effect of all antibiotic combinations based on colistin is not shown. Amikacinbased combinations with additive effect are found out. Insufficient activity of preparations for phagotherapy is demonstrated (no more than 32% isolates are possessed of sensitivity to them). Different preparations with labeled anti-Pseudomonas activity showed differences between the spectrum of antibacterial activity. High incidence rate of secondary phage resistance is detected.

Keywords

• pseudomonas aeruginosa
• antibiotic resistance
• polymyxins
• carbapenems
• antibiotic combinations
• bacteriophages