Background

With a large dynamic range, the colony forming unit (CFU) assay is the gold standard for measuring cell viability. However, it is time- and resource-intensive precluding its deployment in high throughput screens. Drug screens commonly measure cell growth as a proxy to viability, but such assays cannot distinguish drugs which kill cells from drugs which merely slow growth. Furthermore, growth cannot be used to measure drug efficacy against intrinsically slow growing, drug-resistant cells such as those found in biofilms.

Technology Overview

The Geometric Viability Assay (GVA) embeds cells after treatment in a soft gel cast in a 3D ramp. The probability of a colony forming at any position along the ramp is determined by ramp geometry. From a single pipette step, the distribution of the colonies (visible cell masses arising from a single cell) is predicted by an analytic solution enabling CFU calculations across 5 orders of magnitude.

Stage of Development

Technology Readiness Level (TRL): 5

Benefits

• Large dynamic range. Can measure viability over 5 orders of magnitude
• High sensitivity. Capable of finding 1 viable cell in 10,000,000
• 8x reduction in time per experimental condition
• No expensive equipment required to purchase and maintain
• Reduced cost due to higher throughput
• Can be used with different pathogens including: gram-positive bacteria, gram-negative bacteria, and yeast
• Can measure drug effects in non-growing conditions (e.g. biofilms)

Applications

• Screen drug combinations targeting multi-drug resistant bacteria.
• Personalized prediction of an infectious pathogen’s susceptibility to an antibiotic panel for point of care diagnostics.
• Functional genomics screens to identify key regulators of drug sensitivity or resistance.
• Measure drug susceptibility of bacteria within a consortium.