Stressing the System: A Multi-model Testing Regime for Determining Antibiofilm Activity

Background: The evidence implicating biofilms as a cause for wound chronicity is substantial and growing. Biofilm topics are routinely presented at wound care conferences and companies supplying wound care solutions are rushing to fill the need with a multitude of products.

Purpose: There is a need for relevant, robust biofilm models to facilitate the testing of existing therapies and to aid in the development of new ones. However, literature notes the absence of a ‘target’ reference value to ascertain effectiveness and the virtual impossibility of perfectly mimicking an actual infection in the laboratory as a barrier to relevance (Malone 2016).We agree that no one biofilm model is perfect. We understand the multitude of possibilities that may exist in any given chronic wound regarding exudate volume and consistency, bacterial species, host immunity, wound care compliance, nutrition, comorbidities and so forth. What a robust model can do is control for a defined set of parameters and provide a relative idea of efficacy compared to a negative control or a rank order of efficacy between different therapies. What is required but not routinely done is to then change the parameters to be more stringent and gradually test therapies to a worst-case scenario. Routinely, models with a single set of parameters which may demonstrate some degree of product efficacy with debatable relevance to actual chronic wound conditions are published.

Methods: We have employed a suite of test models that are tunable to truly understand the performance of antimicrobial products. Early product development relies on in-vitro test models with higher throughput to select viable candidates. These candidates are then tested in more complex models involving dynamic conditions, ex-planted tissues, and when appropriate in-vivo animal models.

Results: We will show how commonly used antimicrobials perform within a given model as well as how performance changes with varying conditions.