(210b) Heat Effects on Viability, Morphology, and Dispersal of Staphylococcus Epidermidis Biofilms

Authors: 
Beckwith, J., University of Michigan
Solomon, M. J., University of Michigan
Van Epps, J. S., University of Michigan
Bacterial biofilms are a leading cause of hospital-acquired infections and pose a unique challenge to treat. One alternative to the microbiological view of biofilms is to investigate them from the perspective of soft matter. In the context of soft matter, biofilms are analogous to a composition of colloids embedded in a cross-linked polymer gel. The development of biofilms on medical devices can be understood as a consequence of adsorption, growth, and detachment; each effect is governed by self-assembly, fluid mechanics, and transport phenomena which are dependent on fundamental chemical engineering principles. Here we show how fluid dynamics and heat transfer can be applied to prevent and/or remove bacterial biofilms in an in vitro, flow cell model of a dialysis catheter. Using Staphylococcus epidermidis, the most common bacterial species isolated from infected medical devices, we grow biofilms under physiologically relevant flow conditions and expose them to thermal degradation using a pre-warmed fluid that is injected into the model catheter. Using confocal microscopy and image analysis techniques, we establish that exposing biofilms to elevated temperatures causes a significant decrease in the viability of surface-adhered bacteria, as well as an increase in the structural heterogeneity. Additionally, the cellular material debrided during heat exposure was collected and assessed for morphology and viability. Finally, we investigated the coupled effects of heat treatment with the antibiotic vancomycin, on both the surface-adhered biofilm as well as the downstream debrided material. Understanding the response of both surface-adhered and dispersed bacterial cells under thermal stress, is a promising step toward the development of an in situ treatment/remediation method for biofilm growth in medical devices and provides new insight on the infection capabilities of disseminated biofilm material.