Featured Research

from universities, journals, and other organizations

Portable device provides rapid, accurate diagnosis of tuberculosis, other bacterial infections

Date:
May 5, 2013
Source:
Massachusetts General Hospital
Summary:
A handheld diagnostic device first developed to diagnose cancer has been adapted to rapidly diagnose tuberculosis and other important infectious bacteria. Two versions of the portable device combine microfluidic technology with nuclear magnetic resonance 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

A handheld diagnostic device that Massachusetts General Hospital (MGH) investigators first developed to diagnose cancer has been adapted to rapidly diagnose tuberculosis (TB) and other important infectious bacteria. 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.

"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 also have 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."


Story Source:

The above story is based on materials provided by Massachusetts General Hospital. Note: Materials may be edited for content and length.


Journal Reference:

  1. Monty Liong, Anh N. Hoang, Jaehoon Chung, Nil Gural, Christopher B. Ford, Changwook Min, Rupal R. Shah, Rushdy Ahmad, Marta Fernandez-Suarez, Sarah M. Fortune, Mehmet Toner, Hakho Lee, Ralph Weissleder. Magnetic barcode assay for genetic detection of pathogens. Nature Communications, 2013; 4: 1752 DOI: 10.1038/ncomms2745

Cite This Page:

Massachusetts General Hospital. "Portable device provides rapid, accurate diagnosis of tuberculosis, other bacterial infections." ScienceDaily. ScienceDaily, 5 May 2013. <www.sciencedaily.com/releases/2013/05/130505150042.htm>.
Massachusetts General Hospital. (2013, May 5). Portable device provides rapid, accurate diagnosis of tuberculosis, other bacterial infections. ScienceDaily. Retrieved April 25, 2014 from www.sciencedaily.com/releases/2013/05/130505150042.htm
Massachusetts General Hospital. "Portable device provides rapid, accurate diagnosis of tuberculosis, other bacterial infections." ScienceDaily. www.sciencedaily.com/releases/2013/05/130505150042.htm (accessed April 25, 2014).

Share This



More Plants & Animals News

Friday, April 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Fungus Killing Bats, Spreading in US

Deadly Fungus Killing Bats, Spreading in US

AP (Apr. 24, 2014) A disease that has killed more than six million cave-dwelling bats in the United States is on the move and wildlife biologists are worried. White Nose Syndrome, discovered in New York in 2006, has now spread to 25 states. (April 24) Video provided by AP
Powered by NewsLook.com
Blood From World's Oldest Woman Suggests Life Limit

Blood From World's Oldest Woman Suggests Life Limit

Newsy (Apr. 24, 2014) Scientists say for the extremely elderly, their stem cells might reach a state of exhaustion. This could limit one's life span. Video provided by Newsy
Powered by NewsLook.com
Raw: Kangaroo Rescued from Swimming Pool

Raw: Kangaroo Rescued from Swimming Pool

AP (Apr. 24, 2014) A kangaroo was saved from drowning in a backyard suburban swimming pool in Australia's Victoria state on Thursday. Australian broadcaster Channel 7 showed footage of the kangaroo struggling to get out of the pool. (April 24) Video provided by AP
Powered by NewsLook.com
Could Marijuana Use Lead To Serious Heart Problems?

Could Marijuana Use Lead To Serious Heart Problems?

Newsy (Apr. 24, 2014) A new study says marijuana use could lead to serious heart-related complications. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins