Synergistic effects of zinc oxide nanoparticles and Meropenem on biofilm formation in Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the most prominent nosocomial pathogens globally, which causes a major concern due to its multiple virulence factors, including the ability to form biofilms. Due to the increased antibiotic resistance, the efficacy of common antibiotic treatments for P. aeruginosa is limited. This investigation was designed to assess the synergistic effects of meropenem and Zinc Oxide Nanoparticles on the formation of biofilms in P. aeruginosa isolates. In this study, the antibacterial effects of ZnO nanoparticles were investigated against P. aeruginosa isolates from the educational and medical centers in Tehran, Iran. The disc diffusion method (Kirby-Bauer) was employed to identify the antibiotic resistance profiles in 50 isolates of P. aeruginosa. Furthermore, the presence of pslA and bla-VIM genes was determined by Polymerase Chain Reaction (PCR). The bacterial biofilm formation in 30 isolates with pslA gene was evaluated by Microtiter plate method, Congo Red Agar (CRA), and Tube method (TM). The results indicated that 88% of the studied isolates exhibited resistance to meropenem. Our investigation revealed that there is a close relationship between the ability of biofilm formation by the Microtiter Plate method and the presence of pslA. Moreover, the downregulation of pslA gene in ATCC27583 and two clinical isolates that were treated with ½ MIC Zinc Oxide + ½ MIC Meropenem compared with isolates treated with ½ MIC Meropenem and ½ MIC Zinc Oxide was recorded. The combination of antibacterial properties of ZnO nanoparticles with antibiotics can present novel applications for reducing biofilm formation in P. aeruginosa isolates.