Modeling Antibiotic Diffusion in a Microfluidic Biofilm Array to Study Bacterial Responses to Antibiotic Concentrations and Combinations

J. Deng[1], L. Villegas[1], L. Shor[1], A. Vázquez[2], A. Dhummakupt[3], P. Samson[3], and J.P. Wikswo[3]
[1]University of Connecticut, Storrs, CT, USA
[2]Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, Mexico
[3]Vanderbilt University, Nashville, TN, USA

Bacteria within a biofilm typically exhibit higher resistance to antibiotic therapy due to mass transport resistance of the biofilm matrix and/or reduced metabolic activity of cells living within the biofilm interior. The objective of this research was to develop a high-throughput experimental and modeling approach to investigate the effects of colony spacing and concentration on the effectiveness of combinations of antibiotics on these important pathogens. Here we show preliminary results of experiments and COMSOL modeling of a hydrogel-filled microfluidic device able to create transient gradients over a patterned array of P. aeruginosa and S. aureus biofilms. Inhibitory screening and a prior estimation of antibiotic diffusion coefficients within the hydrogel enable modeling predictions to be made that are fully independent of the experimental screening assay. The device design also enables direct observation of the biofilm morphology and the activity of individual cells via fluorescent protein expression and the use of selective stains.

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