The bacterium that causes TB, mycobacteria tuberculosis, comes from a larger family of mycobacteria, certain strains of which can cause lung disease. The most common pathogenic nontubercular mycobacteria are known together as Mycobacterium avium complex, or MAC. Distinguishing MAC-related pulmonary disease (MAC-PD) from TB is difficult, and can take eight weeks or more. Complicating matters, MAC bacteria are ubiquitous in the environment, and a positive culture may mean nothing more than specimen contamination.
Now, researchers have shown in a multi-center study that differentiating MAC-PD from TB can be accomplished in just a few hours using an assay that can identify antibodies specific to MAC.
The research was published in the first issue for April of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
MAC is responsible for a growing proportion of pulmonary disease, but how much is unclear. “There are more cases being reported,” said Dr. Alvin Teirstein, professor of medicine at Mount Sinai School of Medicine. “We are not sure where it was hiding 25 years ago, but there appears to be a growing epidemic over the last 20 years.”
Up to now, distinguishing between MAC and TB largely relied on a suite of clinical signs and obtaining repeatedly positive sputum cultures—a process that was both unwieldy and often unreliable. “About 20 percent of the time the physician might make the wrong determination,” said Dr. Teirstein.
Furthermore, even though initial diagnosis is uncertain, patients whose sputum is positive for acid-fast bacilli are often immediately isolated and sometimes started on a regimen of anti-TB drugs. Isolating non-TB patients and beginning inappropriate treatment regimens not only drains resources that could be used to treat infectious TB, it is a burden and risk to the patient as well. In contrast to TB, MAC is not contagious and sometimes requires no treatment.
“Diagnosis of pulmonary disease due to MAC is complicated and time-consuming,” wrote Seigo Kitada, lead researcher on the study. “In the context of infection control it is particularly important to distinguish between MAC-PD and pulmonary TB.”
To test the efficacy of the immunoassay kit, the researchers acquired specimens from six centers between June 2003 and December 2005. The samples came from 70 patients with MAC-PD; 18 with MAC contamination, 36 with pulmonary TB, 45 with other lung disease and 76 from healthy patients.
They found that found that serum antibody levels to the MAC-specific antigen were higher in patients with MAC pulmonary disease as compared to those with other respiratory diseases, including tuberculosis. The sensitivity and specificity of the serologic test were 84.3% and 100%, respectively. Equally important, the test, took only hours as opposed to the four to eight weeks it takes to determine conventional culture results.
While Dr. Tierstein points out that to be validated, the kit must perform well with different populations and in different locations, as MAC strains can vary from place to place, this is the first multi-center demonstration of the efficacy of such a kit, raising the hope that it may solve the problem of distinguishing MAC-PD from TB and represents a critical step in increasing the accuracy and efficiency in treating patients with MAC-PD and TB.
Keely Savoie | 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
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses