Effect of silver nanoparticles on surface hydrophobicity and biofilm formation in Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli

Biofilms are microbial aggregates that adhere to a substrate as a surface and are surrounded by an exopolysaccharide matrix. The bacteria that make up biofilms are so resistant to antimicrobials and antibiotics that this has led to concerns in the medical community.The aim of this study was effect of silver nanoparticles on surface hydrophobicity and biofilm formation in Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli. This study was performed on 40 bacterial strains including Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Acinetobacter baumannii isolated from Milad Hospital in Tehran. The strains were identified by biochemical tests. Also, biofilm formation by microtiter plate method, surface hydrophobicity by MATH method and sensitivity of strains to silver nanoparticles were evaluated. According to the results obtained in this study, all strains were able to form biofilms and no strains with negative biofilms were observed in the study. The highest effect of silver nanoparticles in this study was observed on strains at concentrations of 0.5, 1 and 2 μg / ml. Also, only 20% of Pseudomonas aeruginosa strains in this study were observed with moderate hydrophobicity and the others of the bacteria were weakly hydrophobic. silver nanoparticles in low concentrations with the effect of low toxicity had the ability to inhibit the biofilm formation of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii. Hydrophobicity in the studied bacteria were weak.