Asynchronous Magnetic Bead Rotation Microviscometer for Rapid, Sensitive, and Label-Free Studies of Bacterial Growth and Drug Sensitivity (original) (raw)
Related papers
2012
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.
Lab on a Chip, 2011
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.
Biosensors & Bioelectronics, 2011
Continuous growth of individual bacteria has been previously studied by direct observation using optical imaging. However, optical microscopy studies are inherently diffraction limited and limited in the number of individual cells that can be continuously monitored. Here we report on the use of the asynchronous magnetic bead rotation (AMBR) sensor, which is not diffraction limited. The AMBR sensor allows for the measurement of nanoscale growth dynamics of individual bacterial cells, over multiple generations. This torque-based magnetic bead sensor monitors variations in drag caused by the attachment and growth of a single bacterial cell. In this manner, we observed the growth and division of individual Escherichia coli, with 80-nm sensitivity to the cell length. Over the life cycle of a cell, we observed up to a 300% increase in the rotational period of the biosensor due to increased cell volume. In addition, we observed single bacterial cell growth response to antibiotics. This work demonstrates the non-microscopy limited AMBR biosensor for monitoring individual cell growth dynamics, including cell elongation, generation time, lag time, and division, as well as their sensitivity to antibiotics.
Rapid bacterial growth and antimicrobial response using self-assembled magnetic bead sensors
Sensors and Actuators B: Chemical, 2014
Despite advances in molecular diagnostics, phenotypic results remain essential, especially due to the ever increasing presence of antimicrobial resistance in healthcare-acquired infections and in foodborne illnesses. Since phenotypic information is still crucial, the objective of this work was to combine the robustness and cost-effectiveness of traditional bacterial culture, and to approach the speed of molecular diagnostic methods. With concentrations as low as 5 × 10 3 CFU/mL, the growth of pathogenic Escherichia coli O157:H7 was detected in 91 ± 4 min, which is on par with reported real-time PCR times used for food microbiology testing. Results were obtained using a 48 sensor prototype device that accepted standard well plates. A sensor with the reported rapid growth monitoring capabilities could dramatically improve the detection time and sensitivity in applications that require rapid phenotypic information, such as with patient samples and food testing.
Continuous growth of individual bacteria has been previously studied by direct observation using optical imaging. However, optical microscopy studies are inherently diffraction limited and limited in the number of individual cells that can be continuously monitored. Here we report on the use of the asynchronous magnetic bead rotation (AMBR) sensor, which is not diffraction limited. The AMBR sensor allows for the measurement of nanoscale growth dynamics of individual bacterial cells, over multiple generations. This torque-based magnetic bead sensor monitors variations in drag caused by the attachment and growth of a single bacterial cell. In this manner, we observed the growth and division of individual Escherichia coli, with 80-nm sensitivity to the cell length. Over the life cycle of a cell, we observed up to a 300% increase in the rotational period of the biosensor due to increased cell volume. In addition, we observed single bacterial cell growth response to antibiotics. This work demonstrates the non-microscopy limited AMBR biosensor for monitoring individual cell growth dynamics, including cell elongation, generation time, lag time, and division, as well as their sensitivity to antibiotics.
Biomicrofluidics, 2019
The need for accurate and efficient antibiotic susceptibility testing (AST) has been emphasized with respect to the emerging antimicrobial resistance of pathogenic bacteria which has increased over the recent decades. In this study, we introduce a microfluidic system that enables rapid formation of the antibiotic concentration gradient with convenient bacterial growth measurement based on color scales. Furthermore, we expanded the developed system to analyze combinatory effects of antibiotics and measured the collective antibiotic susceptibility of bacteria compared to single microfluidic AST methods. By injecting a continuous flow precisely into the channel, the system enabled the concentration gradient to be established between two parallel channels of different antibiotic concentrations within 30 min, before bacteria enter the exponential growth phase. Moreover, the local bacterial growth levels under antibiotic gradient were quantitatively determined by calculating the position-...
2021
Antibiotic resistance in urinary tract infections is a major global challenge and improved cost-effective and high throughput antibiotic susceptibility tests (AST) are urgently needed to inform correct antibiotic selection. We evaluated a high throughput microfluidic test strip for AST and minimum inhibitory concentration (MIC) determination in 20 urinary pathogenic E. coli (UPEC) isolates using six commonly prescribed or therapeutically beneficial antibiotics. The microfluidic MIC performs broth microdilution in 1 microliter volume capillaries, 100 X smaller than standard broth microdilution. Each test strip contains 10 parallel capillaries which are dipped into a single well of a 96 well plate, significantly increasing throughput over a microtitre plate. When tested with clinical UPEC isolates at standardised inoculum density, these devices gave 100% essential agreement (+/- 1 doubling dilution of antibiotic) to the gold standard microplate broth microdilution method described by ...
Rapid antibiotic sensitivity testing in microwell arrays
TECHNOLOGY, 2017
The widespread bacterial resistance to a broad range of antibiotics necessitates rapid antibiotic susceptibility testing before effective treatment could start in the clinic. Among resistant bacteria, Staphylococcus aureus is one of the most important, and Methicillin-resistant (MRSA) strains are a common cause of life threatening infections. However, standard susceptibility testing for S. aureus is time consuming and thus the start of effective antibiotic treatment is often delayed. To circumvent the limitations of current susceptibility testing systems, we designed an assay that enables measurements of bacterial growth with higher spatial and temporal resolution than standard techniques. The assay consists of arrays of microwells that confine small number of bacteria in small spaces, where their growth is monitored with high precision. These devices enabled us to investigate the effect of different antibiotics on S. aureus growth. We measured the Minimal Inhibitory Concentration (...
Antibiotics, 2015
Effective treatment of bacterial infection relies on timely diagnosis and proper prescription of antibiotic drugs. The antimicrobial susceptibility test (AST) is one of the most crucial experimental procedures, providing the baseline information for choosing effective antibiotic agents and their dosages. Conventional methods, however, require long incubation times or significant instrumentation costs to obtain test results. We propose a lab-on-a-chip approach to perform AST in a simple, economic, and rapid manner. Our assay platform miniaturizes the standard broth microdilution method on a microfluidic device (20 × 20 mm) that generates an antibiotic concentration gradient and delivers antibiotic-containing culture media to eight 30-nL chambers for cell culture. When tested with 20 μL samples of a model bacterial strain (E. coli ATCC 25922) treated with ampicillin or streptomycin, our method allows for the determination of minimum inhibitory concentrations consistent with the microdilution test in three hours, which is almost a factor of ten more rapid than the standard method.