Researchers Use Electrical Signalling to Detect Bacteria

Researchers at the University of Warwick have found bacteria can be detected in minutes by zapping them with electricity.

Scientists at the university in the United Kingdom discovered healthy bacteria cells and those inhibited by antibiotics or UV light show different electric reactions. When zapped with an electrical field, live bacteria absorb dye molecules causing the cells to light up so they can be counted. Bacillus subtilis and E. coli were used as model organisms.

Testing commercial products for bacterial contamination can take days. During this time, they can cause significant numbers of illnesses and infections can become life threatening if not identified and treated appropriately.

The researchers’ findings, published in Proceedings of the National Academy of Sciences of the United States of America, could lead to development of medical devices that can rapidly detect live bacterial cells, evaluate the effects of antibiotics on growing bacteria colonies, or identify different types of bacteria and reveal antibiotic-resistant bacteria. One target is quality control in the water, pharmaceutical, food, and beverage industries.

James Stratford, from the School of Life Sciences and spinout company Cytecom, said “the system we have created can produce results which are similar to the plate counts used in medical and industrial testing but about 20 times faster. This could save many people’s lives and also benefit the economy by detecting contamination in manufacturing processes.”

Scientists showed bioelectrical signals from bacteria can be used to determine if they are alive or dead. The approach uses membrane-potential dynamics and electrical stimulation to differentiate between incapacitated and viable cells.

The team developed an experimental tool to study the relation of bacterial electrical signaling. Using it combined with time-lapse microscopy, they showed live and inhibited cells respond to electrical stimulation in opposite directions. A 2.5-second electrical stimulation caused hyperpolarization in unperturbed cells while inducing depolarization in inhibited cells.

Findings offer an approach for rapid detection of proliferative bacteria without observation of actual proliferation or time-consuming calibrations for bacterial species. It can detect proliferative cells within a minute after electrical stimulation.

Researchers founded a start-up company called Cytecom. The firm has been awarded a grant from Innovate UK, a national funding agency, which means devices could be available to researchers and businesses shortly.

The team combined biological experiments, engineering and mathematical modelling.

“This work demonstrates that bacterial electricity can lead to societally important technology, while at the same time gaining fundamental insights into our basic understanding of cells. The tool we developed can offer more opportunities by allowing experiments which were not possible to perform before,” said Munehiro Asally, assistant professor at the University of Warwick.

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NC State Developing New Technology that will Help Farmers Detect Plant Pathogens

The fresh food in your grocery stores could eventually get cheaper thanks in part to new technology being developed at NC State that’ll help farmers protect their crops better and apply just the right amount of chemicals to prevent disease.

When a crop gets diseased, it can spread really quickly in a field, so it’s essential for farmers to detect problems fast.

But, traditional methods of disease detection can take weeks. Now a team of NC State researchers have come up with something that’s much quicker and portable.

The device literally smells disease.

Currently, it’s being tested in a lab run by assistant professor Qingshan Wei of the Emerging Plant Disease & Global Food Security Cluster at NC State.

They’ve detailed their results in a paper published by the Journal Nature.

Here’s how it works in laymen’s terms.

When a plant is diseased, it will actually give off gasses.

To test their proof of concept, Wei’s team puts part of a tomato plant leaf in a sealed glass tube.

The wait about 15 minutes as the air in the sealed vial becomes saturated with volatiles from the plant.

Once enough gas is collected, a device attached to the back of a cell phone is used to suck the air from the vial into a chamber where it’s analyzed.

The gas reacts with a tiny paper strip that’s coated with chemical dots.

The dots change color based on the disease affecting the plant.

The cell phone user then takes a magnified picture of the strip to be used by them as a reference on what chemical treatments need to be applied to the crops to stop the spread of disease.

“You want to know if it’s a bacterial infection or a fungal infection or other type of infection and guide your treatment steps,” said Wei.

Right now, the sniffer device only works on potato leaves and tomato leaves, but Wei’s team is developing sensors which will work with other crops.

The idea for the sensor was built on previous discoveries by other researchers who found out diseased plants gave off certain gasses.

“The leaf is breathing,” said Wei. “It’s exchanging molecules with the air.”

Right now, a farmers only options for figuring out what’s plaguing a crop is either guesswork or sending a sample to as clinical lab where it can take weeks to figure out the pathogen affecting the plants.

By the time the results are sent back to the farmer, the disease could have ruined an entire field of crops.

Once this lab porotype is fully developed, farmers will be able to use it in their fields to get instant results and can minimize the amount of chemical they apply.

“You want to have a rapid decision if you want to apply a fungicide or not,” said Wei.

Deciding how much and what chemical to apply is important because the less that’s applied is better for the environment.

And, saving a crop early will end up keeping prices lower because farmers won’t lose as much in the field.

Actual use of the sniffer is still about a year or so away because as it still needs a little more testing.

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Mesa Biotech to Present Comparative Flu & RSV Detection Analysis with Other FDA-Cleared Molecular Assays at AACC

Mesa Biotech Inc. is a privately-held, molecular diagnostic company that has developed the Accula™ System, an affordable, sample-to-answer, CLIA-waived PCR (polymerase chain reaction) testing platform designed specifically for point-of-care (POC) infectious disease diagnosis. Today, Mesa Biotech announced it will present performance comparisons of its visually read PCR testing platform with other FDA-cleared molecular tests for influenza A/B and respiratory syncytial virus (RSV) assays. The lecture will take place on August 6, 2019 at 1:00 pm in theater 3 of the exhibit hall at the 71st American Association of Clinical Chemistry (AACC) Annual Meeting and Clinical Lab Expo in Anaheim, CA. Additionally, the Accula System's RSV and Flu A/Flu B molecular tests will be on exhibit in Booth 3902 at AACC.

"Antiviral drug treatments are becoming increasingly popular and more widely used. The antivirals work best when taken within 48 hours of symptom onset, therefore highly accurate, POC testing is crucial for healthcare professionals to achieve rapid and accurate confirmation of the infection to enable the best patient outcome," said Hong Cai, Co-founder and Chief Executive Officer, Mesa Biotech, Inc.

Stephen Young, PH.D., Director of Research and Clinical Trials at TriCore Reference Laboratory will present the session titled 'Sample-to-answer, CLIA-waived PCR System with Visually Read Results for POC: Comparative Flu and RSV Detection Analysis with Other FDA-cleared Molecular POC Assays'. The presentation will provide a technology overview and performance characteristics of the visually interpreted, CLIA-waived Accula System that possesses the simplicity, convenience and procedural familiarity of traditional POC rapid immunoassays. Additionally, Dr. Young will provide insight on the user experience with the Accula System.

About Mesa Biotech Inc.

Mesa Biotech designs, develops, manufactures and commercializes next generation molecular diagnostic tests, bringing the superior diagnostic performance of nucleic acid PCR amplification to the point-of-care (POC). Mesa Biotech's Accula™ System consists of a portable, palm-sized dock and single-use, assay-specific test cassettes. This patented system enables healthcare professionals to access actionable, laboratory-quality results at the POC with greater sensitivity and specificity than current infectious disease rapid immunoassay tests. The Accula Flu A/Flu B and the Accula RSV tests have obtained CE Mark in the EU and 510(k) clearance and Clinical Laboratory Improvements Amendments (CLIA) waiver from the U.S. Food and Drug Administration (FDA). Both products are distributed in the US by Sekisui Diagnostics under the Silaris™ brand. Mesa Biotech has also secured a number of strategic agreements for distribution in Europe and Asia.

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Using Quantum Dots and a Smartphone to Rapidly Detect Bacterial Pathogens

A combination of off-the-shelf quantum dot nanotechnology and a smartphone camera soon could allow doctors to identify antibiotic-resistant bacteria in just 40 minutes, potentially saving patient lives.

Staphylococcus aureus (golden staph), is a common form of bacterium that causes serious and sometimes fatal conditions such as pneumonia and heart valve infections. Of particular concern is a strain that does not respond to methicillin, the antibiotic of first resort, and is known as methicillin-resistant S. aureus, or MRSA.

Recent reports estimate that 700,000 deaths globally could be attributed to antimicrobial resistance, such as methicillin-resistance. Rapid identification of MRSA is essential for effective treatment, but current methods make it a challenging process, even within well-equipped hospitals.

Soon, however, that may change, using nothing except existing technology.

Researchers from Macquarie University and the University of New South Wales, both in Australia, have demonstrated a proof-of-concept device that uses bacterial DNA to identify the presence of Staphylococcus aureus positively in a patient sample -- and to determine if it will respond to frontline antibiotics.

In a paper published in the international peer-reviewed journal Sensors and Actuators B: Chemical the Macquarie University team of Dr Vinoth Kumar Rajendran, Professor Peter Bergquist and Associate Professor Anwar Sunna with Dr Padmavathy Bakthavathsalam (UNSW) reveal a new way to confirm the presence of the bacterium, using a mobile phone and some ultra-tiny semiconductor particles known as quantum dots.

"Our team is using Synthetic Biology and NanoBiotechnology to address biomedical challenges. Rapid and simple ways of identifying the cause of infections and starting appropriate treatments are critical for treating patients effectively," says Associate Professor Anwar Sunna, head of the Sunna Lab at Macquarie University.

"This is true in routine clinical situations, but also in the emerging field of personalised medicine."

The researchers' approach identifies the specific strain of golden staph by using a method called convective polymerase chain reaction (or cPCR). This is a derivative of a widely -employed technique in which a small segment of DNA is copied thousands of times, creating multiple samples suitable for testing.

Vinoth Kumar and colleagues then subject the DNA copies to a process known as lateral flow immunoassay -- a paper-based diagnostic tool used to confirm the presence or absence of a target biomarker. The researchers use probes fitted with quantum dots to detect two unique genes, that confirms the presence of methicillin resistance in golden staph

A chemical added at the PCR stage to the DNA tested makes the sample fluoresce when the genes are detected by the quantum dots -- a reaction that can be captured easily using the camera on a mobile phone.

The result is a simple and rapid method of detecting the presence of the bacterium, while simultaneously ruling first-line treatment in or out.

Although currently at proof-of-concept stage, the researchers say their system which is powered by a simple battery is suitable for rapid detection in different settings.

"We can see this being used easily not only in hospitals, but also in GP clinics and at patient bedsides," says lead author, Macquarie's Vinoth Kumar Rajendran.

Reference:

Vinoth Kumar Rajendran, Padmavathy Bakthavathsalam, Peter L. Bergquist, Anwar Sunna. Smartphone detection of antibiotic resistance using convective PCR and a lateral flow assay. Sensors and Actuators B: Chemical, 2019; 298: 126849

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IIT Guwahati Researchers Develop Tri-Layer Dielectric Organic Field Effect Transistor to Rapidly Detect Bacteria

Indian Institute of Technology Guwahati Researchers have developed a low-cost, hand-held device to detect bacteria. This Research by IIT Guwahati will enable rapid detection of bacteria, which is important not only in healthcare, but also in anti-bioterrorism measures and environmental monitoring applications.

Bacterial infection is a common cause of morbidity and mortality worldwide and despite development of a range of antibiotics, the challenge continues to lie in detecting and diagnosing bacterial infection early on, as present detection techniques tend to be time-consuming.

The research team led by Prof Parameswar K Iyer, Department of Chemistry, and Prof Siddhartha S Ghosh, Department of Biosciences and Bioengineering, IIT Guwahati, has developed this novel, low-cost, bio-compatible sensor that can detect bacteria almost instantaneously without the need for cell culture and microbiological assays. The Organic Field Effect Transistor (OFET)-based bacterial diagnostic device has been shown to have the ability to detect 103 cfu mL-1 of bacteria and distinguish between Gram positive and Gram negative types.

Their work has been patented as well as published in the July 2019 issue of the reputed peer-reviewed Journal of Materials Chemistry A of the Royal Society of Chemistry.

At present, the detection of bacteria in body fluids is done in laboratories. The cells that are derived from the patient are initially cultured or grown so that enough of the bacterial cells are available for microbiological analysis.

Explaining the need to develop faster and easier methods to detect bacteria, Prof. Iyer says, “Current diagnostic processes are frustratingly time-consuming, especially when time is of the essence in administering treatment.” While newly developed techniques such as real time qPCR can detect bacteria faster than conventional assay-based methods, they are restricted by the need for expensive apparatuses and trained personnel. What would be useful are hand-held rapid detection kits like those used for blood sugar monitoring and pregnancy detection.”

The IIT Guwahati team consisting of Dr Anamika Dey, Dr Ashish Singh, Dr Deepanjalee Dutta (all three former PhD scholars from Center for Nanotechnology, IITG), Prof Siddhartha Sankar Ghosh and Prof Parameswar Krishnan Iyer, brings portable bacterial detection kits closer to reality. The sensor detects the charges on the cell walls of bacteria.

Highlighting the functionality of the device, Prof Ghosh said, “It is known that Gram positive bacteria such as S pneumoniae, have different cell wall compositions than Gram negative bacteria such as the common E coli. Such asymmetric cell wall organisations could alter flow of electrons at the channel of OFETs during their detection”.

The important breakthrough by the team was in developing and using an Organic Field Effect Transistor (OFET) to detect this surface charge. The OFET is an electronic device that works on the principle that charges in the vicinity of the channels of certain semiconductors can induce a current in them. Thus, the charges on the surface of the bacterium, induces a current in the OFET, which is registered and read.

The OFET devices developed by the team consists of a unique and hybrid tri-layer dielectric system built on simple glass and flexible PET (a kind of plastic) substrates, and can operate at ultra-low operating voltages. The team has shown that this OFET sensor can not only detect bacteria, but also differentiate between Gram positive and Gram negative bacteria.

“Not only have we shown the sensing capabilities of this portable OFET device, but we have also shown the mechanism by which sensing occurs and elucidated the role of bacterial wall in distinguishing various bacterial types”, added Prof. Iyer on the significance of this latest interdisciplinary research work.

The OFET-based ready-to-use diagnostic tool will facilitate rapid detection and diagnosis at the point of care. The current device is particularly useful for the detection of bacteria primarily for water-borne diseases. These sensors will also be useful in instantaneous detection of time-critical illnesses such as meningitis.

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