Impact of Chitosan and Silver Nanoparticles Laden with Antibiotics on Multidrug-Resistant Pseudomonas aeruginosa and Acinetobacter baumannii

Abstract

Background: The emergence of multidrug-resistant (MDR) Pseudomonas aeruginosa and Acinetobacter baumannii is a profound therapeutic concern requiring innovative antimicrobials. Nanotechnology has unlocked new promises, and nanoparticles (NPs) have been used either alone or in combinations against MDR bacteria to overcome antibacterial resistance. Objectives: We aimed to evaluate the antibacterial activity of silver and chitosan nanoparticles alone and in combination with either ciprofloxacin or gentamicin against A. baumannii and P. aeruginosa strains. Methods: The antibacterial activities of synthesized materials were evaluated using microdilution broth, disc diffusion, and drop diffusion methods and the expression of target genes by the quantitative real-time polymerase chain reaction. Results: The result of disc diffusion and drop diffusion methods for chitosan when assessed against MDR or wild type P. aeruginosa and MDR A. baumannii at different concentrations ranged from 8 - 35 mm and 6 - 15 mm respectively, while the range was lower in the nanoparticle form of chitosan. The results also showed that the expression of efflux pump adeB in A. baumannii and mexB in P. aeruginosa decreased after treatment with chitosan, chitosan nanoparticles, and silver nanoparticles; thus, they may be good candidates as efflux pump inhibitors. Conclusions: The present study showed the superiority of antibacterial and anti-efflux pump activity of chitosan over silver nanoparticles against MDR P. aeruginosa and A. baumannii.