"We're hopeful that this more sensitive method, which is both simple and inexpensive, will improve diagnosis in patients," said lead researcher Kevin Fennelly, M.D., M.P.H., an associate professor in the UF College of Medicine's department of medicine and Southeastern Tuberculosis Center, and the UF Emerging Pathogens Institute.
The new technique, which involves vacuum filtering a sputum sample treated with household bleach and other simple chemicals through a small filter, could dramatically improve TB diagnoses globally, particularly in settings where the disease is common and resources are limited. It is especially useful when the presence of only a small number of bacteria in the test sample makes it hard to detect TB. The researchers are refining the technique in hopes of developing a cost-effective product that can be used globally.
Funded by the World Health Organization and the Núcleo de Doenças Infecciosas infectious disease institute in Brazil, the study appears online and in an upcoming print edition of the Journal of Clinical Microbiology.
TB is a treatable disease caused by a microbe called Myocardium tuberculosis. It most often affects the lungs, but can also target organs such as the brain, spine and kidneys. Symptoms of active disease include a chronic cough, sputum production and coughing up blood. TB spreads from person to person through the air.
Once the leading cause of death in the U.S., TB has been largely under control in Western nations. Still, more than 11,000 U.S. cases were reported in 2010, the latest year for which there is comprehensive data. That year, almost 9 million people around the world were diagnosed with TB and almost 1.5 million died from it. TB causes more deaths than any other bacterial infection and is the most common killer of people living with HIV.
"TB is still a tremendously important disease worldwide and control efforts are greatly hindered by lack of simple, inexpensive diagnostics that could be used at the point of care," said Elizabeth Talbot, M.D., a Dartmouth College infectious diseases and TB diagnostics expert who was not involved in the UF research. "What Dr. Fennelly has done is capitalize on existing infrastructure of microscopy to try to improve performance of that prevalent diagnostic tool."
The most widely used way to confirm TB infection is to use a microscope to identify and count disease-causing bacteria in sputum smeared onto a glass slide. This so-called direct-smear method also helps health professionals figure out how likely people are to pass on the disease, what treatment decisions should be made, and how well patients are responding to treatment. Although the method has been in continuous use for more than a century, it can be unreliable, catching cases only about half of the time, on average.
Part of the problem is that sometimes sputum samples don't contain many bacteria, making it hard to detect TB. Concentrating bacteria onto a small area could help improve detection accuracy, and although previous efforts have led to improvements, they tend to require expensive equipment or technical know-how. In some cases, gains were offset by loss of sample or safety concerns. So the quest for a low-cost, simple, effective method led back to the trusty microscope.
In the early 1980s researchers vacuum-filtered sputum samples to trap TB bacteria onto quarter-sized filters that were then viewed under a microscope. But the filters hung over the sides of standard microscope slides, posing a health hazard and preventing proper inspection. So Fennelly and his team decided to try smaller-than-a-dime filters that fit neatly onto microscope slides and that concentrated the bacteria even more.
Among 314 patients in Brazil suspected as having TB, but not yet in treatment, the small-filter method detected 89 percent of cases, compared with 60 percent detection when samples were concentrated by the currently used method of rapid spinning, and 56 percent detection when sputum smears were looked at directly under the microscope. Furthermore, the small-filter method identified almost three-quarters of TB-positive cases that had been incorrectly reported as negative based on the traditional technique.
Fennelly and collaborators are now teaming with the humanitarian organization Médecins Sans Frontières, translated as "Doctors Without Borders," to test the method in western Uganda, where many people have both TB and HIV. They're comparing it again with the traditional direct-smear method and with a sophisticated DNA-based test that can also detect whether bacteria are drug resistant.
Both types of technique have their place — high-tech tools would be most feasible in referral centers, but on the front lines, the small-filter microscope method can perform an invaluable service, the researchers say.
"A point-of-care dipstick that can say yes or no is the Holy Grail, but we're a long way from there," Fennelly said. "'Microscope' has become a dirty word in the TB diagnostics world — but almost every clinical laboratory in the world has one."
Czerne M. Reid | EurekAlert!
NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures
17.11.2017 | National Institute of Standards and Technology (NIST)
High speed video recording precisely measures blood cell velocity
15.11.2017 | ITMO University
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
20.11.2017 | Life Sciences
20.11.2017 | Materials Sciences
20.11.2017 | Life Sciences