Resumo

About 80% of biomedical devices-related infections are associated to biofilm formation. Biofilms are structured microbial communities that grow adhered to biotic or abiotic surfaces. This complex mode of life is more resistant to host defenses and antibiotics when compared to planktonic bacteria. The surface of an implantable/inserted device such as cardiac valves, vascular and urinary catheters, joint prostheses and others becomes ideal environment for providing bacterial adhesion, the first step of biofilm formation. Given the high levels of biofilm infection, the emergence of antibiotic-resistant bacteria combined with the slow progress in identifying new antimicrobial agents, combat strategies have inestimable clinical value. Due to the ability of surface-active compounds to remain exactly where the biofilm develops, non-ionic surfactants were screened in respect to antibiofilm activity. The aim of this work was to coat a polystyrene surface with the, previously selected, active surfactant against Staphylococcus epidermidis biofilm. Polystyrene 96-well microplates were covered with an alcoholic surfactant solution in concentrations below, above and on the surfactant CMC and were extensively washed. Staining with crystal violet technique measured the biofilm inhibition as well as images by scanning electron microscopy (SEM). The surface was characterized by atomic force microscopy and contact angle measurements. Cell-surface hydrophobicity assay was performed to estimate the bacterial hydrophobicity index. The coated polystyrene surface was able to inhibit up to 90% of Staphylococcal biofilm formation even after 100 consecutive surface washes. It is suggested the existence of an unfavorable threshold roughness of biofilm formation, of about 2 nm. The bacterial hydrophobicity was not changed; instead the surface became highly hydrophilic. Our work presents a simple method of coating employing a synthetic surfactant to avoid S. epidermidis biofilm formation on the polystyrene surface, accounting a promising result in the field of biomaterials and hospital infections.