Biofilm Surface Density Determines Biocide Effectiveness

Abstract

High resistance of biofilms for chemical challenges is a serious industrial and medical problem. In this work a gradient of surface covered with biofilm has been produced and correlated to the effectiveness of different commercially available oxidative biocides. The results for thin Escherichia coli biofilms grown in rich media supplemented with glucose or lactose on glass or poly methyl methacrylate surfaces indicate that the effectiveness of hydrogen peroxide or chlorine dioxide and quaternary ammonium compounds is inversely proportional to the fraction of the surface covered with the biofilm. In areas where biofilm covered more than 90% of the available surface the biocide treatment was inefficient after 60 min of incubation. The combined effect of oxidant and surfactant increased the effectiveness of the biocide. On the other hand, the increased biofilm viscoelasticity reduced biocide effectiveness. The results emphasize differential biocide effectiveness depending on the fraction of the attached bacterial cells. The results suggest that biofilm biocide resistance is an acquired property that increases with biofilm maturation. The more dense sessile structures present lower log reductions compared to less dense ones.

Bacterial Density and Biofilm Structure Determined by Optical Coherence Tomography

“…Biofilms mostly grow on surfaces in aqueous environments, that range from marine and industrial to biomedical environments 1,2 . Biofilms have complicated, heterogeneous structures that influence their resistance to mechanical or chemical challenges 3–5 , such as fluid shear or detergents and other antimicrobials. However, microscopic methods available for non-destructive analysis of biofilm structure, while not requiring staining, are scarce and frequently only provide low resolution images covering a small field of view.…”

Acute Mastoiditis With Intracranial Complications in a Young Adult With History of Cranioplasty: The Rule in the Post-Antibiotic Era

“…Surgical removal of the infected material is necessary because it functions as a diffusion barrier decreasing the antibiotic penetrance. MMA surfaces have a higher viscosity and thus a lower biocide agent penetration with lower rates of bacterial killing than those seen in other materials [14].…”

Current Knowledge on Listeria monocytogenes Biofilms in Food-Related Environments: Incidence, Resistance to Biocides, Ecology and Biocontrol

“…Generally, previously reported studies consider that the amount of adhered viable cells in biofilms is directly related with its resistance to antimicrobials [ 127 , 128 ]. Nevertheless, in L. monocytogenes , viable biomass present in the biofilm does not give any certain indication about the difficulty of this pathogen to be eliminated from a given contamination site.…”