Development of a high throughput and low cost model for the study of semi-dry biofilms

Abstract

The persistence of microorganisms as biofilms on dry surfaces resistant to the usual terminal cleaning methods may pose an additional risk of transmission of infections. In this study, the Centre for Disease Control (CDC) dry biofilm model (DBM) was adapted into a microtiter plate format (Model 1) and replicated to create a novelin vitromodel that replicates conditions commonly encountered in the healthcare environment (Model 2). Biofilms ofStaphylococcus aureusgrown in the two models were comparable to the biofilms of the CDC DBM in terms of recovered log(10)CFU well(-1). Assessment of the antimicrobial tolerance of biofilms grown in the two models showed Model 2 a better model for biofilm formation. Confirmation of the biofilms' phenotype with an extracellular matrix deficientS. aureussuggested stress tolerance through a non-matrix defined mechanism in microorganisms. This study highlights the importance of conditions maintained in bacterial growth as they affect biofilm phenotype and behaviour.