Minimum biofilm eradication

It is important to note that antimicrobial and biofilm resistance are two different characteristics though some materials show both properties at the same time. Antimicrobial materials do not automatically prevent biofilm formation and vice versa. Antimicrobial surfaces could kill bacteria on contact but if dead bacteria cell debris blocks the active biocidal surface, biofilm formation could eventually occur. For example, quaternary anunonium polymers can effectively kill bacteria but when the surface is fouled with dead bacteria debris, biofilm formation is inevitable [188]. Materials with antibiofilm properties will repel the bacterial adhesion very effectively but may not kill the bacteria when they do colonize the surface. PEG surfaces are well known to repel bacteria adhesion. However, PEG surfaces show little antimicrobial activity. Quantitative antibiofilm efficacy tests can be divided into two categories static (minimum biofilm eradication concentration assay, MBEC) and dynamic (flow cell assay). In addition, SEM is a semiquantitative assay, which is discussed in Section 2.5. 

The toxicity of 44 metals to the biofilms and planktonic cells of Pseudomonas fluorescens was measured and expressed as minimum inhibitory concentration, minimum bactericidal concentration, and minimum biofilm eradication concentration. Linear regression analyses wa-e conducted to determine the relationships between the measured toxicity values and the following physicochemical parameters standard reduction-oxidation potential, electronegativity, the solubility product of the corresponding metal-sulfide complex, the Pearson softness index, electron density, and the covalent index. Each of the physicochemical parameters was significantly (P < 0.05) correlated with one or more of the toxicity measurements. Heavy metal ions were found to show the strongest correlations between toxicity and physicochemical parameters. 

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