Fighting Infectious Diseases with Antimicrobial Agents using Microfluidic Platforms

The aim of this project is to screen for novel antimicrobial compounds to combat the emerging threat of antibiotic resistance in Gram-negative pathogens.

Here we propose to exploit substances exuded by previously uncultured organisms dwelling in soil and marine sediments. We will exploit miniaturised devices based on microfluidics to isolate and grow microorganisms in their natural environments and investigate, with single-cell resolution, their interaction with Gram-negative bacterial pathogens in collaboration with Prof Rick Titball at the University of Exeter and Dr Sarah Harding at Dstl. Thanks to the miniaturised and portable nature of our experimental platform relying on extensive microfluidic and microscopy capabilities within Dr Pagliara's group (Pagliara et al., 2014 Nature Materials 13: 638; Otto et al., 2015 Nature Methods 12: 199), we will be able to investigate microorganisms cultured from a variety of environments including marine sediments and soil. Alternatively, fluorescence activated cell sorting will be employed to isolate single organisms from the different environments.

Antibiotic activity of the extracts from these organisms will be tested against pathogens such as Burkholderia thailandensis (a Containment Level 2 surrogate for Burkholderia pseudomallei), Francisella tularensis LVS (a Containment Level 2 surrogate of Francisella tularensis) and Coxiella burnetii strain Phase 2 (that can be handled at Containment Level 2) under the supervision of Dr Sarah Harding at DSTL. The antibiotic activity of extracts from the microorganisms cultured in their natural environments will be determined in a number of in vitro assays which will include determining the minimum inhibitory concentrations of the compounds, time kill assays to determine how quickly the compound has an effect, intracellular cell culture assays and studies involving the wax moth Galleria mellonella (if deemed appropriate). Other bacterial species may be included if the compound/s show significant activity. These in vitro assays are routinely performed at Dstl with both novel and commercial off the shelf products with both Containment Level 2 and 3 pathogens using established methods and models.

Finally, those microorganisms that will show potent activity against such pathogens will be sequenced at the Exeter Sequencing Service, this allowing for their identification either as previously cultured or uncultured organisms.