S13: Validation of a Biofilm Disinfectant Efficacy Test

In biofilm efficacy testing, the goal is to grow a biofilm that is relevant to the environment where a disinfectant will be applied then test the disinfectant under “real use” conditions. The strategy the Standardized Biofilm Methods Laboratory (SBML) at the Center for Biofilm Engineering promotes for biofilm methods development is based upon partitioning biofilm methods into four discreet steps, then standardizing each step separately.  The steps required for testing the efficacy of an anti-biofilm treatment are:  1) grow a relevant and repeatable biofilm using a biofilm reactor, 2) treat a mature biofilm with biocide or antibiotics, 3) remove a representative biofilm sample, and 3) analyze the sample for a quantitative and/or qualitative estimate of kill and/or removal as a result of the treatment.  A company needing to test their product chooses the most relevant combination of grow, treat, sample and analyze methods that best serve their particular needs.  

The SBML is collaborating with the EPA to develop a standard method for testing the efficacy of liquid disinfectants against biofilm bacteria.  The EPA has developed a draft protocol known as the “Single Tube” method.  In this method, the efficacy of a disinfectant is tested against a Pseudomonas aeruginosa biofilm grown in the CDC biofilm reactor (ASTM Method E2562). This presentation will discuss the advantages and disadvantages of the single tube method as well as results of a two-laboratory collaborative study.