MBEC assay

The MBEC assay described is designed for antibiotics rather than polyurethane materials. Therefore, Russell et al. [191] modified this method to evaluate acrylate-urethane coating s performance. Salicylic acid was first conjugated with an acrylate group to form a polymerizable monomer. This monomer was then copolymerized with urethane acrylate via UV free radical polymerization (Figure 2.36). The peg cones on... 

Figure 2.34 MBEC assay, (a) Biofilms form on the polyst5rene pegs of the MBEC device when planktonic bacteria adsorb to the surface. These bacteria become irreversibly attached and grow to form mature biofihns. Biofilms are encased in sUme, which is sometimes visible to the naked eye. Planktonic cells are also shed from the surface of biofilms, which serves as the inoculum for CA determinations, (b) The peg lid has 96 identical plastic pegs. This hd fits into a trough with channels designed to guide an inoculum across the surface of the pegs. The peg lid fits into a standard 96-well microplate as weU, which is used to set up serial dilutions of antimicrobials.

Bardounitis, E., Huddleston, W., Ceri, H. and Olson, M. E., 2001. Characterization of biofilm growth and biocide susceptibility testing of Mycobacterium phlei using the MBEC assay system. FEMS Microbiology Letters 203,... 

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. 

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