New Microfluidic-Microwave Ring Resonator Biosensor to Detect Pathogenic Bacteria

Canadian researchers utilized the lab-on-a-chip microfluidic technology to develop a new biosensor for real-time detection of pathogenic bacteria.

Bacteria are all around us—in the air, on objects, and both inside and on the surfaces of the human body. They are so small that hundred thousands of them could fit on thetip of a hair. Bacteria are usually harmless, but some of them can causedisease in people who consumed contaminated food and in those with open woundsthat are exposed to dirty water.

Risk of bacterial infection

Bacterial infection is an important public health problem, resulting in a range of diseases and levels of resistance. For example, there are about 1.3 million tuberculosis-related deaths worldwide caused by mycobacterium tuberculosis bacteria every year. At the same time, Salmonella, Escherichia coli, and Listeria are the leading causes of illness and death in the United States due to bacterial pathogens transmitted commonly through food.

While these infectious diseases are highly treatable at an early stage, the current methods of diagnosing infections and performing antibiotic susceptibility are expensive, time-consuming, and labor-intensive. Typically, it takes about two to five days to obtain accurate and reliable diagnosis results. The delays in diagnosis and treatment may result in higher mortality and morbidity due to prolonged disease and the development of complications, as well as increased risk of further transmission of infection.

Real-time detection of pathogenic bacteria

In a recent study published in Nature Scientific Reports, a group of researchers from Canada has utilized the lab-on-a-chip microfluidic technology to develop a biosensor for speedy detection of pathogenic bacteria. The microfluidic chip, made of soft lithography, was injected with bacterial samples and incorporated with a microwave microstrip ring resonator. By sending a microwave signal through the sample, the device is capable of analyzing and then generating a profile of existing bacteria quickly and accurately.

Having tested the device on various situations of Escherichia coli bacteria, the researchers demonstrated that near-immediate responses can be achieved for detecting bacteria concentration at various pH values. The device also enabled direct observation and enumeration of bacteria. This could benefit clinical microbiology laboratories by automating the workflow of antibiotic susceptibility and increasing the capabilities for the diagnosis and handling of bacterial infections.

This study opens new doors to reshape the future diagnosis of pathogenic bacteria. Further experiments are needed to assess the feasibility of rapid diagnosis and management of different infections.

Reference: 

Narang, R. et al.Sensitive, Real-time and Non-Intrusive Detection of Concentration and Growth of Pathogenic Bacteria using Microfluidic-Microwave Ring Resonator Biosensor. Scientific Reports, 8:15807. DOI: 10.1038/s41598-018-34001-w

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Mobile Device by UCLA Makes the Detection of Parasitic Infections Faster and More Sensitive

Parasitic infections affect hundreds of millions of people, posing a serious public health threat worldwide. For example, sleeping sickness and Chagas disease are neglected tropical diseases that are caused by the bloodborne Trypanosoma parasite. Historically given little attention, these devastating diseases affect people mainly in sub-Saharan Africa and South America, causing enormous socioeconomic burden.

Optical microscopy of bodily fluid samples by trained medical experts remains one of the most common approaches to diagnose parasitic infections in bodily fluids. However, clinically relevant parasite concentrations in bodily fluids can be extremely low. Because conventional optical microscopy typically has a very small imaging volume, it often struggles to provide the sensitivity needed for early diagnosis. Moreover, the task becomes even more challenging when parasitic infections in the blood needs to be detected. Because there are billions of blood cells in each milliliter of blood, and they cause occlusion, making the task of detecting parasites in blood a needle-in-a-haystack problem.

Researchers at the UCLA Henry Samueli School of Engineering have developed an inexpensive and portable platform that can rapidly detect motile parasites in bodily fluids automatically. Using their platform, more than 3 mL of a bodily fluid sample can be imaged and analyzed within 20 min, providing a throughput that is orders of magnitude better than traditional optical microscopy-based examination.

The research, published in Light: Science & Applications, was led by Aydogan Ozcan, Chancellor's Professor of Electrical and Computer Engineering at UCLA and the associate director of the California NanoSystems Institute at UCLA, along with Kent Hill, a Professor in the Department of Microbiology, Immunology, and Molecular Genetics at UCLA.

Instead of directly capturing a still image of the fluid sample and searching for parasites, this unique platform takes a different approach and detects motion within the sample. It records high-frame-rate videos of the holographic patterns of the sample illuminated with laser light. Then, a motion analysis algorithm analyzes these captured videos at the micro-scale and converts the locomotion of the target parasites within the sample into a signal spot, which is detected and counted using artificial intelligence.

"Although motility is a common feature of various parasites and other disease-causing micro-organisms, its use as a fingerprint for diagnosis is highly underexplored and our work provides landmark results, highlighting this unique opportunity." said Ozcan.

"Our platform can be considered as a motion detector in the microscopic world, which locks onto any moving objects within the sample." said Yibo Zhang, a UCLA doctoral student and the first author of this study, "Locomotion is used as both a biomarker and a contrast mechanism to distinguish parasites from normal cells."

The proof of concept of this device has been demonstrated using Trypanosoma parasites, which have multiple subspecies that cause sleeping sickness and Chagas disease. The detection limit of the device was quantified as 10 parasites per milliliter of whole blood, which is about 5 times better than the state-of-the-art parasitological detection methods. This improved detection limit may lead to a better capability to detect sleeping sickness and Chagas disease at an earlier stage, which is essential to improve the cure rate and reduce prevalence. Beyond trypanosomes, the authors also demonstrated the use of their device to detect Trichomonas vaginalis, highlighting that their technique is applicable to various parasites and motile microorganisms.

The UCLA device is compact and lightweight (1.69 kg) and the cost of the prototype is less than $1850, which can be reduced to less than $800 when manufactured in larger volumes. "Thanks to its high sensitivity, ease-of-use, reduced cost and portability, we believe our technique can improve parasite screening efforts, especially in resource-poor areas and endemic regions." said Hatice Ceylan Koydemir, a UCLA postdoctoral scholar, who is a co-author of this study. Other co-authors of the manuscript are Michelle M. Shimogawa, Sener Yalcin, Alexander Guziak, Tairan Liu, Ilker Oguz, Yujia Huang, Bijie Bai, Yilin Luo, Yi Luo, Zhensong Wei, Hongda Wang, Vittorio Bianco, Bohan Zhang, and Rohan Nadkarni.

This study is supported by the NSF Engineering Research Center (ERC, PATHS-UP), NIH and the Howard Hughes Medical Institute (HHMI).

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New Field Test Discerns Between Ebola and Lookalike Fevers

At the close of the 2014-2016 West Africa Ebola crisis, the Paul G. Allen Foundation identified diagnostic gaps as one of the major deficiencies that had contributed to the outbreak’s spread.

“The standard diagnostic tests that exist are very good, but they’re hard to do out in the field in the middle of an outbreak like we saw in West Africa,” said John Connor, a virologist at the Boston University National Emerging Infectious Diseases Laboratory (NEIDL). Instead, samples need to be sent to a facility capable of running the tests, which means it could be several days between taking a sample and getting a diagnosis.

Connor, in collaboration with researchers from Columbia University, the National Institutes of Health Integrated Research Facility, clinical collaborators from Senegal and the Hemorrhagic Fever Lab in Guinea, as well as Becton, Dickinson and Company (BD), came together and proposed an idea for a new kind of diagnostic that would bridge critical gaps in the field.

“We set out to create a rapid, point-of-care diagnostic that could look for malaria, Ebola and other pathogens that are often found in these regions,” said Connor, who is also an associate professor of microbiology at Boston University School of Medicine. The Allen Foundation, based in Seattle, WA, agreed to fund the project.

While there are myriad ways to design rapid, portable diagnostics, the solution pursued by the team was based on a test that could be stored without refrigeration, which is typically hard to maintain along supply routes to rural outbreak areas. That’s why the researchers liked the idea of designing a portable material identification system built on magnetic beads and glass-encased gold nanoparticles.

The system, surface-enhanced Raman scattering (SERS), is based upon the idea that light scatters off of different types of molecules in distinct ways. As such, specific molecules have distinct light-scattering signatures (or unique barcodes) that can be detected. Although the barcodes can be weak on their own, the addition of gold particles amplifies the detectable light signal making the barcode easier to detect.

“Gold amplifies the barcode by about a million times,” Connor said.

Working with BD, which was developing SERS for other applications, Connor and his collaborators helped design a system capable of differentiating between the different barcodes of the malarial parasite and Ebola virus, as well as Marburg and Lassa viruses, two other deadly hemorrhagic fevers found in the same regions of Africa where Ebola outbreaks are common.

At the start of the test, a small sample of blood is mixed with magnetic beads coated in antibodies that attract each of the four infectious agents. If the blood contains malaria-causing parasites or Ebola, Marburg or Lassa viruses, the pathogens glom onto the magnetic beads. At the same time, similar antibodies on glass-encased gold nanoparticles also attach to the pathogens, creating a link between the magnetic and gold beads. Then, inside a small machine, the materials are concentrated into one spot by magnetic force and hit with a small laser beam.

Analyzing the barcode of light that flashes back from a sample, the machine can rapidly provide a readout of the presence of malarial parasites or Ebola, Marburg or Lassa viruses. From sample-taking to final readout, the entire process can be completed in 30 minutes or less. The development of the system, and experimental data showing its efficacy in animal and human blood samples, was published Wednesday in Science Translational Medicine.

Once the sample is added to the tube, there is no need to reopen the tube because all the reagents are already inside, noted Yanis Ben Amor, one of the study's authors. Amor is an associate research scientist and the executive director of the Center for Sustainable Development at Columbia University in New York. For the technicians carrying out the testing, “this was seen as a tremendous advantage in the context of highly infectious samples," he said.

Designed to go anywhere, the system’s components can be battery operated and can fit inside a standard-sized backpack, the researchers said.

“The implications for getting good diagnostics to remote places are huge,” Connor said.

Connor said the value of the diagnostic is not just in identifying who has a contagious illness and who does not, but also in creating better relations with the communities at risk of becoming infected. If patients can rapidly be diagnosed and treated for illness, it can foster trust while immediately helping clinicians identify who should be quarantined and who should be sent home with antimalarial medicines.

Connor said the system could be custom-tailored to detect and differentiate virtually any combination of pathogens, whether they be bacterial, viral, fungal or parasitic.

“The reason I find this system so promising is that it can diagnose more than one thing simultaneously, which is important in the real-world context of infectious diseases,” Connor said. “The disease landscape is complicated and pathogens aren’t operating in isolation from one another.”

Source: MDDI

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WPI Researchers Developing a Biosensor That Can Speed Diagnosis of Clostridium difficile

Researchers at Worcester Polytechnic Institute (WPI) are developing a biosensor that doctors and nurses can use to quickly detect Clostridium difficile (C. diff), a dangerous and sometimes fatal gastrointestinal infection. The sensor is designed to be the heart of a handheld device that can be used onsite in doctor’s offices and nursing homes, providing results in minutes instead of days, avoiding the need to send samples out to commercial labs, and making it possible to start treatment earlier, when it is likelier to be more successful.

Highly contagious, C. diff is the most common infectious cause of diarrhea in hospitalized patients The bacteria also causes nausea, dehydration, weight loss, colitis, kidney failure, and an increased white blood cell count. The longer treatment is delayed, the sicker patients become and the harder the infection is to cure. C. diff infects more than 500,000 people each year in the United States, of whom more than 29,000 die within 30 days of diagnosis, according to the Centers for Disease Control and Prevention. It is responsible for as much as $4.8 billion per year in health care costs. A major complication of antibiotic therapy, C. diff generally occurs in older adults who have received antibiotics in hospitals or long-term care facilities.

“C. diff is a very serious disease, especially for the elderly,” said Hong Susan Zhou, associate professor of chemical engineering at WPI and principal investigator for the biosensor research program, which is funded by a $350,000 award from the National Science Foundation. “When people are in the hospital and receiving antibiotics, they are very easily infected and it’s very dangerous. When people start having symptoms of diarrhea, it’s not easy tell if it’s C. diff or not. If they can be diagnosed in the early stages, then it’s more easily treated.”

C. diff is typically detected by culturing a stool sample, a test that has a high rate of false negatives, requires specialized equipment and expertise, and cannot be done at most points-of-care facilities. At present, no single commercially available test offers strong sensitivity and portability, as well as rapid turnaround time and low cost. Inexpensive point-of-care diagnostics for C. diff are needed to improve detection, therapy, and treatment cost, Zhou said “Right now, it takes 24 to 48 hours to receive a C. diff diagnosis,” she noted. “People can get much sicker in just that short period of time.”

Starting in 2012, Zhou began looking for a better and faster way to detect C. diff. That research resulted in a microwave-size biosensor prototype, which she built and demonstrated in her lab in 2015. With the current grant, she is working with Yuxiang (Shawn) Liu, assistant professor of mechanical engineering at WPI and co-PI on the project, to shrink the device to make it portable, and to use nanostructures and new microfluidics techniques to make it more sensitive.

The miniaturized biosensor Zhou and Liu are developing uses electrochemical detection (ECD), an extremely selective and sensitive diagnostic technique, which will enable a C. diff infection to be

The biosensor, left, uses antibodies attached to an electrode to detect the C. diff bacteria. The channels etched into the acrylic microfluidic device will bring even tiny samples to the electrode, located in the chambers at either end.

diagnosed much earlier. The biosensor has an electrode with antibodies attached. When C. diff bacteria bind to the antibodies, they trigger an electrical change that signals the presence of an infection. This process takes just a few minutes, as comparedto the one to two days needed for the traditional lab culture.

The 2015 prototype used gold nanoparticles, laid flat, and a traditional microfluidic platform made of PDMS, a silicon-based organic polymer. That prototype would have been difficult to scale up for mass production, Zhou said. The new device will use 3D gold nanostructures, which have more surface area for the antibodies to adhere to, making the biosensor more sensitive and allowing it to be much smaller than the original prototype.

Liu is developing a new microfluidic platform for the sensor that will enable the stool sample to flow more easily toward the electrode. He is replacing the traditional polymer with an acrylic and will use a laser to cut tiny channels into it. The new platform will be easier to fabricate and to integrate with the new electrode, which Liu also will help fabricate. The goal is to create a reusable handheld biosensor that can make a diagnosis with just a drop of stool, much less than is needed for current lab tests.

It will also be designed to be usable without any special training, making it possible for tests to be conducted on site. “For use in point-of-care facilities, it will be important for it to be easier and less expensive to use,” said Liu.

The technology used in the biosensor can be adapted to test for other types of infectious bacteria, including salmonella, bacterial meningitis, and E. coli. It may even be able to check for cancer biomarkers, Zhou said.

The research team also includes three PhD students: Zanzan Zhu and Zhiru Zhou from Zhou’s lab and Yundong Ren from Liu’s lab. Hanping Feng, a professor at the University of Maryland, will supply the antibodies used in the study.

Source: Worcester Polytechnic Institute 

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Handheld Gadget to Provide Rapid Food Quality Testing

A microbiological detection device will help speed up the measurement of contamination in raw meat, thus minimising costs and food waste.

Foodborne diseases are a major public health concern worldwide. Every year an estimated 600 million – about 1 in 10 people – fall ill after eating contaminated food and 420 000 die, according to the World Health Organization. To help address food safety, the EU-funded FRESHDETECT project is developing a portable tool that will determine the microbiological quality of meat products.

A product flyer on the project website notes that the handset determines the "total viable count (TVC) in raw meat without extracting samples and without incubation." It uses a fluorescence spectroscopy process that directs an intense blue light onto the surface of the meat and measures the characteristic fluorescence signatures and the bacterial flora. "The TVC is then calculated using a reliable analysis algorithm to ascertain the microbiological quality of the product. The measurements are non-invasive and last only a few seconds. The results are displayed directly on the device immediately after the measurement."

The device can store up to 2 000 measurements. The results can be transferred to a PC any time via a USB port. As stated in the same product flyer: "Potential fields of application include rapid tests for the in-house control of meat across the entire meat handling and processing chain, as well as delay-free quality monitoring in the receiving and shipping areas."

New dimension

In a news article on the 'FoodNavigator' news website, managing director of project coordinator FreshDetect GmbH Oliver Dietrich said the innovation "creates a new dimension in food safety." According to CORDIS, the "device enables non-invasive microbiological testing without additional operational or maintenance costs." The target users include slaughterhouses, cutting plants, meat processing companies, retailers, wholesalers and butchers. The project aims to bring its "current prototype (TRL7) [technology readiness level 7] to business success with commercialization to these users," CORDIS adds.

In the same news article Dietrich says: "FreshDetect will successively expand its applications to include other food such as fish, dairy products, fruit and vegetables. The focus is not only on bacterial contamination, but also on the detection of pesticides, herbicides, origin, age (degree of ripeness) and other factors."

The ongoing FRESHDETECT (FRESHDETECT – food safety – fast and reliable) project also tackles food waste, which creates about 8 % of all human-caused greenhouse gas emissions. Some 88 million tonnes of food are wasted in the EU every year, with associated costs estimated at EUR 143 billion, according to the European Commission. CORDIS emphasises that "the FreshDetect technology offers a so far unmatched level of food process control allowing an optimization of the food production and minimizing food waste."

The project website notes that although the device has been on the market since the summer of 2017, "it has undergone a series of tests since 2016 that are carried out in conjunction with quality-focused companies in the meat industry." It adds: "We currently offer software datasets for various types of meat. Other datasets for detecting TVC are under development. We are also developing a technology for detecting TVC through transparent packaging (MAP, vacuum)."

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3M Earns AOAC® Performance Tested Methods Certification for Rapid Campylobacter Test

3M Food Safety announced today that the 3M™ Molecular Detection Assay 2—Campylobacter, a rapid molecular test method launched earlier this year, has earned Performance Tested MethodsSM (PTM) Certificate number 111803 from the AOAC® Research Institute. The assay utilizes Loop-Mediated Isothermal Amplification (LAMP) technology to overcome the complex instrumentation requirements of traditional, PCR tools, simplifying the testing process and giving technicians greater control and better efficiency.

The AOAC-PTM designation validates the 3M Molecular Detection Assay 2 - Campylobacter with 3M™ Campylobacter Enrichment Broth as an improvement and/or equivalent alternative to USDA FSIS and ISO reference methods for detecting Campylobacter jejuni, Campylobacter coli and Campylobacter lari. An independent lab tested the technology on a variety of matrices including whole raw chicken carcass rinses, raw poultry parts rinses, raw ground poultry rinses, raw turkey carcass sponges and breaded chicken nuggets. Inclusivity/exclusivity and robustness tests were performed as well to assess the assay’s performance.

“We are excited to receive this certification from the AOAC Research Institute,” said Cynthia Zook, 3M Food Safety commercialization manager. “LAMP technology continues to perform exceptionally well compared to conventional tests. We’re proud to be a part of a sea-change in the industry as we continue to innovate and create technologies like this one that are as simple, accurate, fast and reliable as possible.”

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SpeeDx Receives CE-IVD Mark for ResistancePlus® GC Gonorrhea Test

SpeeDx Pty. Ltd. announced it has received CE-IVD marking for its ResistancePlus® GC assay that detects both the sexually transmitted infection (STI) N. gonorrhoeae, and sequences in the gyrA gene of the bacteria associated with susceptibility to ciprofloxacin (Cipro), a previously used front-line antibiotic treatment. Currently, ceftriaxone ̶ a painful intramuscular injection ̶ combined with azithromycin, is the front-line treatment for gonorrhea in the U.S. However, ceftriaxone represents one of the last remaining antibiotics used for multi-drug-resistant infections and needs to be utilized sparingly so as not to increase resistance to the drug. Already, there are strains of gonorrhea that are resistant to this treatment.

SpeeDx’s new test will allow doctors to confidently and cost-effectively treat up to 70% of gonorrhea infections with a single oral dose of ciprofloxacin because the test establishes disease susceptibility to ciprofloxacin prior to prescribing.

"The ResistancePlus GC test is the first innovation in gonorrhea treatment in decades,” said Dr. Jeffrey Klausner, Professor of Medicine and Public Health at David Geffen School of Medicine and Fielding School of Public Health, University of California, Los Angeles. “With the continued spread of multi-drug gonorrhea, this test can make a real difference.”

Recent surveillance data shows that susceptibility to ciprofloxacin is as high as 70% in some regions and greater than 50% across the majority of countries contributing surveillance data. [1-4]

In response to the clear utility of ciprofloxacin, the British Association of Sexual Health and HIV (BASHH) have recently drafted new gonorrhea management guidelines that include the preferential use of ciprofloxacin over ceftriaxone if antimicrobial susceptibility testing results are available prior to treatment. [5]

“We used a similar test at UCLA in Los Angeles and found that doctors liked the test and were much more likely to prescribe a safer and simpler medicine like oral Cipro tablets instead of using injections like Ceftriaxone,” reports Dr. Klausner.

“ResistancePlus GC is an important next step in our ResistancePlus portfolio and is a welcome addition in managing the extensive antibiotic resistance in N. gonorrhoeae infections,” said Colin Denver, CEO for SpeeDx. “We are already seeing high interest in this test with its clear role in maintaining stewardship of the limited antibiotics still available to treat gonorrhea.”

ResistancePlus GC is the first commercially available molecular test* providing ciprofloxacin susceptibility information and is well placed to support current laboratory molecular testing workflows. “If more doctors use the ResistancePlus GC assay, patients will have a better choice when it comes to treatment and we might make a big difference in controlling antibiotic resistant gonorrhea,” adds Dr. Klausner. “Untreatable gonorrhea is a real threat ̶ use of the ResistancePlus GC assay might stop that.''

*available where CE-mark is accepted, not available in the U.S. or A.U.

About Gonorrhea
N. gonorrhoeae is a bacterium causing gonorrhea, a sexually transmitted infection most frequently causing urethritis in men and cervicitis in women. Gonorrhea can result in infertility or ectopic pregnancy and also increases the risk of acquiring other STIs, including HIV. Transmission from infected mothers to newborns during birth can result in gonococcal conjunctivitis, an infection in the eye (ophthalmia neonatorum).

Prevalence and incidence rates of gonorrhea have been increasing around the world, with corresponding increasing rates of resistance to commonly used antibiotics. [6] Recent studies suggest N. gonorrhoeae is threatening to become untreatable as resistance continues to develop against all known antibiotic treatments. [6] The currently recommended front-line treatment, ceftriaxone, is the last known effective antibiotic, and several extensively drug resistant strains have now been isolated exhibiting resistance to this and many other available treatments. [7,8] Global management strategies for antimicrobial resistance highlight gonorrhea as a priority infection to manage, with more effective use of diagnostic tools listed as a key focus for future development. [9]

About ResistancePlus®
ResistancePlus® kits are multiplex qPCR tests for detection of infectious diseases and antibiotic resistance markers, respectively. Powered by proprietary PlexZyme® and PlexPrime® technologies, the product line offers high multiplexing capability for better, more streamlined infectious disease management. ResistancePlus test offer more than detection, supporting resistance guided therapy by providing actionable information for laboratories and clinicians alike.

References
1. Harris SR et al. Lancet Infect Dis Published online May 15th 2018.
2. Lahra MM et al. Australian Gonococcal Surveillance Programme annual report, 2015.
3.Heffernan H et al. Antimicrobial resistance and molecular epidemiology of gonococci in NZ, 2014-5.
4.  Kirkcaldy RD et al. MMWR Surveillance Summaries July 15, 2016 / 65(7);1–19.
5. Fifer H. et al. 2018 UK national guideline for the management of infection with Neisseria gonorrhoeae (Draft).
6. Unemo, M. & Jensen, J.S. 2016. Nat. Rev. Urol..268. Published online 10 Jan 2017. doi:10.1038/nrurol
7. PHE Health Protection Report Volume 12, Number 11. 2018.
8. AU DoH Media Statement April17th 2018.
9. Rapid Risk Assessment 7 May 2018. Stockholm: ECDC; 2018.

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Rapid Detection of Foodborne Pathogens using Volatile Organic Compounds (VOCs)

A researcher at University of Malaya, Malaysia, has developed a real-time method based on specific volatile organic compounds (VOCs) to detect dangerous bacteria causing foodborne diseases in raw chicken.

The World Health Organisation reported that there were more than 600 million cases of foodborne diseases globally in 2010, causing more than 155,000 deaths worldwide. Several surveillance studies in Malaysia have shown that as high as 9 out of 10 raw chickens in the market are positive for Salmonella and C. jejuni contamination. It was reported that approximately 35—88 percent of raw chicken in Malaysia were contaminated with Salmonella; while C. jejuni was detected in 50—90 percent of farmed chickens and 30—45 percent of raw chicken in the market.

The increased scale of food production and global food trading have raised the risk of failures in our food safety monitoring system to detect foodborne pathogens. Unfortunately, the conventional laboratory-based testing approaches of raw chicken are too slow and can no longer meet the demands of today's large-scale food production. It currently takes two to seven days to complete. A major problem in the current approaches to detect foodborne pathogens is that products must be sacrificed when tested, making the process an expensive affair as it reduces profit margins and raises price. Although new molecular approaches have been adopted to speed up the detection time, the widespread use of this technology is hampered by challenges such as high operational cost and dependency of highly-skilled labour. The technology also suffers from low performance fidelity which is caused by biological interference.

Dr. Chai Lay Ching, food microbiologist from Faculty of Science, University of Malaya (UM), proposed a solution to identify pathogenic bacteria in food based on the detection of specific volatile organic compounds (VOCs) produced by bacteria. Microorganisms are known to emit specific VOCs as gases during the process of breaking down food. The VOCs are a diverse group of carbon-based chemicals that are volatile at ambient temperature and can be detected through smell. Different types of bacteria produce their own VOC signatures. These findings have led the researcher to develop a novel and rapid method to detect bacterial spoilage in food products in a real-time fashion and non-destructive manner, and named her as one of the three winners for the Malaysian L'Oréal-UNESCO for Women in Science Award.

VOCs analysis has been used in clinical diagnosis of various bacterial diseases in humans, such as detection of Clostridium difficile, C. jejuni and Vibrio cholerae in patients' stool. Preliminary laboratory results showed a distinctive VOC-profile associated with C. jejuni in specific laboratory conditions, suggesting the potential of VOC-based biosensors or electric noses that can sniff out these highly pathogenic bacteria in food.

"I accidentally found that Campylobacter produces a very specific scent when we grow them on the agar plate. This allowed me to correctly identify samples with Campylobacter from the negatives ones," Dr. Chai explained.

The findings from this study will generate a database of volatilome of foodborne associated Salmonella and C. jejuni-contamination in raw chicken and different carbon substrates. This work is key for future development of a real-time monitoring system that meet the ideal high-throughput detection criteria. It can be automated, is easy to perform and instantly detects contamination. The application will be key in saving lives and reducing morbidities-associated with these bacteria, as well as helping the food industry to save cost. The successful completion of this project will lead to a better understanding of bacterial metabolism and adaption in different types of substrates, which will help us understand the impact of environment on bacterial growth.

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Ultrasensitive Rapid Diagnostic Test Outperformed Regular Rapid Tests in Identifying Asymptomatic Malaria Infections

A recently developed ultrasensitive rapid diagnostic test outperformed regular rapid diagnostic tests in identifying asymptomatic malaria infections, but was still inferior to loop-mediated isothermal amplification, or LAMP, according to study findings.

Writing in Clinical Infectious Diseases, researchers said there is a growing need for accurate tests to identify asymptomatic malaria infections, which may aid in the elimination of the disease.

“The primary objective of the study was to determine the sensitivity and specificity of different diagnostic tests for malaria, including [rapid diagnostic tests (RDTs)], [ultrasensitive RDTs (uRDTs)], LAMP, microscopy and quantitative real-time PCR (qRT-PCR),” Dylan R. Pillai, MD, PhD, a clinician-scientist at the University of Calgary, and colleagues wrote. “The secondary objectives were to determine epidemiological characteristics for malaria and whether asymptomatic individuals harboring malaria were anemic compared to uninfected persons using highly accurate ultrasensitive diagnostics.”

In a cross-sectional study, Pillai and colleagues assessed 562 asymptomatic individuals in the Gambella region of southwest Ethiopia to establish epidemiological characteristics associated with asymptomatic malaria. Participants were tested for malaria by LAMP, ultrasensitive qRT-PCR and three RDTs, including the uRDT Alere Malaria Ag P.f (Abbott), CareStart (Accessbio) and SD Bioline Malaria Ag P.f (Abbott).

According to the findings, compared with qRT-PCR, LAMP had the highest sensitivity (92.6%; 95% CI, 86.4-96.5). The uRDT Alere test was next (33.9%; 95% CI, 25.5-43.1), followed by CareStart (14%; 95% CI, 8.4-21.5); microscopy (7.3%; 95% CI, 2.7-15.3) and SD Bioline (5%; 95% CI, 1.8-10.5).

Additionally, Pillai and colleagues compared the sensitivity of the tests for detecting Plasmodium falciparum specimens only and found the sensitivity for uRDT Alere was 50% (95% CI, 38.8-61.3), whereas SD Bioline was 7.3% (95% CI, 2.7-15.3).

According to the study, every 3.2% increase in the prevalence of asymptomatic malaria caused a decrease in hemoglobin by 1 g/dL when based on a multivariate regression analysis and compared with the gold standard, qRT-PCR. Furthermore, 4.8% deletions were observed in HRP2.

“These data show that uRDT is superior to traditional RDT in detecting asymptomatic individuals, but uRDT is still inferior to molecular techniques, with LAMP having the highest sensitivity to detect malaria compared to qRT-PCR,” Pillai and colleagues wrote. “Further studies are required to identify the optimal diagnostic test for interrupting malaria transmission in elimination studies. Longitudinal studies are also required to investigate the potential clinical benefits of treating asymptomatic malaria.”

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