Interspecies interactions can enhance Pseudomonas aeruginosa tolerance to surfaces functionalized with silver nanoparticles

Development of anti-fouling surfaces is a major challenge in materials research. Microorganisms growing as biofilms have enhanced tolerance to antimicrobial strategies including antibiotics and antiseptics complicating the design of anti-fouling surfaces. Silver nanoparticles (AgNPs) are a promising antimicrobial technology with broad spectrum efficacy with a reduced likelihood of microorganisms developing resistance to the technology. This study tested the efficacy of new immobilized AgNP-modified surface technology against three common opportunistic pathogens grown either as monocultures or as cocultures. The presented study fills a gap in the literature by quantifying the efficacy of immobilized AgNP particles against multispecies biofilms. Polyethylene (PE) surfaces functionalized with the AgNPs were highly effective against Pseudomonas aeruginosa biofilms reducing viable cell counts by 99.8 % as compared to controls. However, the efficacy of the AgNP-modified PE surface was compromised when P. aeruginosa was cocultured with Candida albicans. Interspecies interactions can strongly influence the efficacy of anti-fouling AgNP coatings highlighting the need to test surfaces not only against biofilm phenotypes but under conditions representative of applications including the presence of multispecies consortia.