Asynchronous magnetic bead rotation (AMBR) biosensor in microfluidic droplets for rapid bacterial growth and susceptibility measurements

Abstract

Inappropriate antibiotic use is a major factor contributing to the emergence and spread of antimicrobial resistance. The long turnaround time (over 24 hours) required for clinical antimicrobial susceptibility testing (AST) often results in patients being prescribed empiric therapies, which may be inadequate, inappropriate, or overly broad-spectrum. A reduction in the AST time may enable more appropriate therapies to be prescribed earlier. Here we report on a new diagnostic asynchronous magnetic bead rotation (AMBR) biosensor droplet microfluidic platform that enables single cell and small cell population growth measurements for applications aimed at rapid AST. We demonstrate the ability to rapidly measure bacterial growth, susceptibility, and the minimum inhibitory concentration (MIC) of a small uropathogenic Escherichia coli population that was confined in microfluidic droplets and exposed to concentrations above and below the MIC of gentamicin. Growth was observed below the MIC, and no growth was observed above the MIC. A 52% change in the sensor signal (i.e. rotational period) was observed within 15 minutes, thus allowing AST measurements to be performed potentially within minutes.

Rapid phenotypic antimicrobial susceptibility testing using nanoliter arrays

“…However, these methods require high-resolution optics and timelapse investigation of multiple locations, making them expensive and complicated to multiplex and parallelize for high-volume clinical use. Other contributions for reducing AST time bypass the need to image individual cells while remaining sensitive by implementing other unique detection schemes such as sensitive changes in mass measured with a microchannel-embedded cantilever (20,21), asynchronous magnetic bead rotation (22), or by speeding up cell growth with higher oxygen delivery using highsurface-to-volume-ratio microchannels (23). However, these schemes often involve complicated readouts and have not been demonstrated in a format that promotes automated data collection or multiplexing for different antibiotics or antibiotic concentrations.…”

Evaluation of a Microbial Sensor as a Tool for Antimicrobial Activity Test of Cosmetic Preservatives

“…The flow-cell system enabled sequential analysis, and each analysis was completed within 30 min. This is quite rapid as compared to the agar dilution method as well as other alternative methods proposed thus far Nett et al, 2011;Pina-Vaz et al, 2001;Sinn et al, 2012;Sinn et al, 2011 . Another advantage of microfluidics is that it is easy to prepare a variety of mixed solutions of multiple agents at arbitrary proportions Hosokawa et al, 2011;Jang et al, 2011;Lee et al, 2009 .…”

New Technologies for Rapid Bacterial Identification and Antibiotic Resistance Profiling

“…Monitoring surface-bound magnetic beads, 39,40 the direct magnetic properties of cells, 25 bacteria confined to fluidic channels, 34 and morphological changes that occur upon antibiotic exposure 23,24,39,40 all represent promising methods for bacterial profiling. For all of these approaches, algorithm development is critical given the heterogeneity of bacterial cells in clinical specimens.…”