Antibiotic-Induced Biofilm Formations in Pseudomonas aeruginosa Strains KPW.1-S1 and HRW.1-S3 are Associated with Increased Production of eDNA and Exoproteins, Increased ROS Generation, and Increased Cell Surface Hydrophobicity.

Abstract

Pseudomonas aeruginosais a medically important opportunistic pathogen due to its intrinsic ability to form biofilmson different surfaces as one of the defense mechanisms for survival. The fact that it can formbiofilms on various medical implants makes it more harmful clinically. Although variousantibiotics are used to treatPseudomonas aeruginosainfections, studies have shown thatsub-MIClevels of antibiotics could inducePseudomonasbiofilm formation. Thepresent study thus explored the effect of the aminoglycoside antibiotic gentamicin on the biofilm dynamics of two Pseudomonas aeruginosa strains KPW.1-S1 and HRW.1-S3.Biofilm formation was found to be increased in the presence of increased concentrations of gentamicin. Confocal,scanning electronmicroscopy,and other biochemical tests deduced that biofilm-forming components exoproteins, eDNA, and exolipids as exopolymeric substances inPseudomonas aeruginosabiofilms were increased in the presence of gentamicin. An increase in reactive oxygen species generation along with increased cell surface hydrophobicity was also seen for both strains when treated with gentamicin. The observed increase in the adherence of the cells accompanied by the increase in the components of exopolymeric substances may have largely contributed to the increased biofilm production by the Pseudomonas aeruginosa strains under the stress of the antibiotic treatment.