Two papers appearing in the journals Nature Communications and Nature Nanotechnology describe portable devices that combine microfluidic technology with nuclear magnetic resonance (NMR) to not only diagnose these important infections but also determine the presence of antibiotic-resistant bacterial strains.
On this 2.5- by 7.5-cm cartridge, DNA extracted from sputum samples is amplified in the chambers on the left. TB-specific sequences are magnetically labeled in the microfluidic mixing channels in the center and detected by passage through the micro-NMR coil on the right.
Credit: Center for Systems Biology, Massachusetts General Hospital
"Rapidly identifying the pathogen responsible for an infection and testing for the presence of resistance are critical not only for diagnosis but also for deciding which antibiotics to give a patient," says Ralph Weissleder, MD, PhD, director of the MGH Center for Systems Biology (CSB) and co-senior author of both papers. "These described methods allow us to do this in two to three hours, a vast improvement over standard culturing practice, which can take as much as two weeks to provide a diagnosis."
Investigators at the MGH CSB previously developed portable devices capable of detecting cancer biomarkers in the blood or in very small tissue samples. Target cells or molecules are first labeled with magnetic nanoparticles, and the sample is then passed through a micro NMR system capable of detecting and quantifying levels of the target. But initial efforts to adapt the system to bacterial diagnosis had trouble finding antibodies – the detection method used in the earlier studies – that would accurately detect the specific bacteria. Instead the team switched to targeting specific nucleic acid sequences.
The system described in the Nature Communications paper, published on April 23, detects DNA from the tuberculosis bacteria in small sputum samples. After DNA is extracted from the sample, any of the target sequence that is present is amplified using a standard procedure, then captured by polymer beads containing complementary nucleic acid sequences and labeled with magnetic nanoparticles with sequences that bind to other portions of the target DNA. The miniature NMR coil incorporated into the device – which is about the size of a standard laboratory slide – detects any TB bacterial DNA present in the sample.
Tests of the device on samples from patients known to have TB and from healthy controls identified all positive samples with no false positives in less than three hours. Existing diagnostic procedures can take weeks to provide results and can miss up to 40 percent of infected patients. Results were even stronger for patients infected with both TB and HIV – probably because infection with both pathogens leads to high levels of the TB bacteria – and specialized nucleic acid probes developed by the research team were able to distinguish treatment-resistant bacterial strains.
The Nature Nanotechnology paper, being issued online today, describes a similar system using ribosomal RNA (rRNA) – already in use as a bacterial biomarker – as a target for nanoparticle labeling. The investigators developed both a universal nucleic acid probe that detects an rRNA region common to many bacterial species and a set of probes that target sequences specific to 13 clinically important pathogens, including Streptococcus pneumoniae, Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA).
The device was sensitive enough to detect as few as one or two bacteria in a 10 ml blood sample and to accurately estimate bacterial load. Testing the system on blood samples from patients with known infections accurately identified the particular bacterial species in less than two hours and also detected two species that had not been identified with standard culture techniques.
While both systems require further development to incorporate all steps into sealed, stand-alone devices, reducing the risk of contamination, Weissleder notes that the small size and ease of use of these devices make them ideal for use in developing countries. "The magnetic interactions that pathogen detection is based on are very reliable, regardless of the quality of the sample, meaning that extensive purification – which would be difficult in resource-limited setting – is not necessary. The ability to diagnose TB in a matter of hours could allow testing and treatment decisions within the same clinic visit, which can be crucial to controlling the spread of TB in developing countries."
Hakho Lee, PhD, of the MGH Center for Systems Biology. co-senior author of both papers, notes that the system will alsohave important applications in developed countries. "The capacity of the system not only to identify bacterial species but also to differentiate factors such as antibiotic resistance will help clinicians treat patients with the 'right' drugs from the start, which also helps reduce the emergence of treatment-resistant strains. The fact that this device requires only a tiny drop of the sample to be tested will be helpful in instances when specimens can be hard to obtain, such as treating children or seniors."
Weissleder is a professor of Radiology, and Lee is an assistant professor of Radiology at Harvard Medical School. Co-lead authors of the Nature Communications paper are Monty Liong, PhD, of the MGH CSB and Anh Hoang, PhD, of the MGH Center for Engineering in Medicine; co-authors include investigators from Harvard School of Public Health and the Broad Institute. Hyun Jung Chung, PhD, of the MGH CSB is lead author of the Nature Nanotechnology report.
Support for both studies includes National Institutes of Health grants R01EB004626, R01EB010011, R01HL113156, P41EB002503, HHSN268201000044C, R01HL113156 and T32CA79443. The MGH has applied for patents on the technology described in this paper.
Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $775 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, reproductive biology, systems biology, transplantation biology and photomedicine. In July 2012, MGH moved into the number one spot on the 2012-13 U.S. News & World Report list of "America's Best Hospitals."
Sue McGreevey | EurekAlert!
Further reports about: > Bird Communication > Broad Institute > DNA > Escherichia coli > MGH > Medical Wellness > Nanotechnology > Nature Immunology > Nature Nanotechnology > Portable breast scanner > bacterial species > bacterial strains > blood sample > cancer biomarker > developing countries > health services > magnetic nanoparticles > neurodegenerative disorder > nucleic acid sequence > radiology > resistant bacteria > synthetic biology
Antioxidants cause malignant melanoma to metastasize faster
09.10.2015 | University of Gothenburg
Finding cannabinoids in hair does not prove cannabis consumption
07.10.2015 | Universitätsklinikum Freiburg
Nondestructive material testing (NDT) is a fast and effective way to analyze the quality of a product during the manufacturing process. Because defective materials can lead to malfunctioning finished products, NDT is an essential quality assurance measure, especially in the manufacture of safety-critical components such as automotive B-pillars. NDT examines the quality without damaging the component or modifying the surface of the material. At this year's Blechexpo trade fair in Stuttgart, Fraunhofer IZFP will have an exhibit that demonstrates the nondestructive testing of high-strength automotive body parts using 3MA. The measurement results are available in a matter of seconds.
To minimize vehicle weight and fuel consumption while providing the highest level of crash safety, automotive bodies are reinforced with elements made from...
The MICADO camera, a first light instrument for the European Extremely Large Telescope (E-ELT), has entered a new phase in the project: by agreeing to a Memorandum of Understanding, the partners in Germany, France, the Netherlands, Austria, and Italy, have all confirmed their participation. Following this milestone, the project's transition into its preliminary design phase was approved at a kick-off meeting held in Vienna. Two weeks earlier, on September 18, the consortium and the European Southern Observatory (ESO), which is building the telescope, have signed the corresponding collaboration agreement.
As the first dedicated camera for the E-ELT, MICADO will equip the giant telescope with a capability for diffraction-limited imaging at near-infrared...
Self-driving cars will be on our streets in the foreseeable future. In Graz, research is currently dedicated to an innovative driver assistance system that takes over control if there is a danger of collision. It was nature that inspired Dr Manfred Hartbauer from the Institute of Zoology at the University of Graz: in dangerous traffic situations, migratory locusts react around ten times faster than humans. Working together with an interdisciplinary team, Hartbauer is investigating an affordable collision detector that is equipped with artificial locust eyes and can recognise potential crashes in time, during both day and night.
Inspired by insects
An interdisciplinary team of researchers has built the first prototype of a miniature particle accelerator that uses terahertz radiation instead of radio...
At present, tiny magnetic whirls – so called skyrmions – are discussed as promising candidates for bits in future robust and compact data storage devices. At...
01.10.2015 | Event News
30.09.2015 | Event News
17.09.2015 | Event News
09.10.2015 | Earth Sciences
09.10.2015 | Life Sciences
09.10.2015 | Life Sciences