Asynchronous Magnetic Bead Rotation Microviscometer for Rapid, Sensitive, and Label-Free Studies of Bacterial Growth and Drug Sensitivity

Abstract

The long turnaround time in antimicrobial susceptibility testing (AST) endangers patients and encourages the administration of wide spectrum antibiotics, thus resulting in alarming increases of multi-drug resistant pathogens. A method for faster detection of bacterial proliferation presents one avenue towards addressing this global concern. We report on a label-free asynchronous magnetic bead rotation (AMBR) based viscometry method that rapidly detects bacterial growth and determines drug sensitivity by measuring changes in the suspension’s viscosity. With this platform, we observed the growth of a uropathogenic Escherichia coli isolate, with an initial concentration of 50 cells per drop, within 20 minutes; in addition, we determined the gentamicin minimum inhibitory concentration (MIC) of the E. coli isolate within 100 minutes. We thus demonstrated a label-free, micro-viscometer platform that can measure bacterial growth and drug susceptibility more rapidly, with lower initial bacterial counts than existing commercial systems, and potentially with any microbial strains.

RETRACTED: Using silica molecular sieve modified Fe3O4 particles as supporting matrix for oxygen sensing: Construction, morphology, characterization and sensing performance

“…Some precursive efforts have reported magnetic chemosensors, such as magnetic beads and Janus sensors, which offers a perfect solution for site-specific migration [20][21][22][23][24][25][26][27]. The possibility of combining a magnetic component with oxygen sensors has been confirmed by reports from Kopelman and Klimant and their oxygen sensors based on magnetic particles [28][29][30][31][32][33][34][35][36].…”

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 .…”

Detecting de-gelation through tissue using magnetically modulated optical nanoprobes (MagMOONs)

“…For example, in 1950, Frances Crick monitored the rotational motion of micron sized aspherical particles in response to pulsed magnetic fields to measure the viscosity in chick fibroblasts [21]. Optical tracking of rotating magnetic particles was used to monitor changes in drag during growth of single bacteria on MagMOONs [22] to monitor changes in shape of single cancer stem cells [23], to measure the viscosity of butterfly saliva [24], and to detect bacteria based on changes in viscosity when bacteria excrete biofilm polymers [25]. In addition, particle rotation has been used to track intracellular transport [26, 27].…”

“…When the viscosity of the environment surrounding the bead changed or the effective volume changed (e.g. due to a bacterium binding onto the bead surface), the rotational period of the bead changed accordingly [25, 28]. This method has high sensitivity at the single bacterium and single cell level [29].…”