A geometry-dependent, force balance-driven model of Staphylococcus epidermidis biofilm cell cluster detachment

TL;DR

This paper introduces a geometry-dependent, force balance-based model for biofilm detachment that incorporates cluster properties and EPS disruption, providing new insights into detachment dynamics.

Contribution

The model uniquely accounts for cluster geometry, local bacterial and EPS arrangements, and EPS disruption effects, advancing predictive understanding of biofilm detachment.

Findings

Cluster size and shape are influenced by EPS disruption levels.

Model predictions align with experimental biofilm microstructure data.

EPS weakening increases detachment frequency and alters cluster morphology.

Abstract

Biofilms, bacteria cells surrounded by a self-produced polymeric matrix, are common on medical devices and lead to many hospital infections. The biofilm lifecycle includes disassembly and dispersion, where bacteria clusters detach from the biofilm, circulate in the bloodstream, and potentially colonize secondary infection sites. Existing models often simplify detachment to a function of biofilm thickness or extracellular polymeric substance (EPS) density, without tracking properties of detached clusters that impact their biological fate, including cluster size and morphology. Addressing this gap, our detachment model accounts for drag and adhesion in tagged sections of the biofilm determined by the cluster geometry and local arrangement of bacteria and EPS. A stickiness parameter controls local EPS adhesion strength, which is modulated to disrupt (or compromise) EPS biomass. We specifically model the detachment of clusters from a Staphylococcus epidermidis biofilm grown for 24 hours. Experimental data for biofilm microstructural features are utilized to benchmark the simulated biofilm, which is then subjected to different EPS disruption levels. We examine parameters that influence detached biofilm cell cluster frequency, size, and shape, providing mechanistic insights into how compromised EPS influences detachment dynamics. This integrated modeling framework is a significant advance in the predictive capabilities for biofilm detachment processes.