ASTM E2799: Minimum Biofilm Eradication Concentration (MBEC) Assay® Method

The MBEC Assay® (ASTM E2799) approach was designed to address the well-established fact that microbes growing in a biofilm may be up to 100 or even 1000 times less sensitive to antimicrobial agents.

Biofilms occur in situations where microbes are allowed to survive on a surface for a period of time. This may occur in the context of implanted medical devices (i.e., artificial joints), chronic wounds and large burns. Biofilms may also occur within pipelines, on high touch surfaces, and in hard-to-reach areas. The resulting reduced sensitivity to antimicrobial agents can result in a failure to eradicate the biofilm, despite the agent being effective against the organism when tested by traditional methods. The MBEC Assay® Kit (ASTM E2799) was designed to address this deficiency by providing a relatively high throughput method to determine the efficacy of antimicrobial agents against pre-formed biofilms.

The MBEC Assay® method consists of first growing 96 nearly identical biofilms on a 96-peg lid. The biofilms are then exposed to increasing concentrations of the antimicrobial agent. After the prescribed challenge time, the remaining cells are recovered and quantified. Similar to the MIC assay, the MBEC Assay® (ASTM E2799) system generates cut-off values to determine the concentration of antimicrobial required to be effective. This information is useful for determining the feasibility and effectiveness associated with a particular antimicrobial agent for applications involving removing existing biofilms.