Instrument designed for biological pathogen monitoring can detect tuberculosis surrogate

An instrument originally designed for detecting the malicious use of biological pathogens has potential for use in the public health sector to rapidly screen people for tuberculosis.

In experiments over the past year, a research team at Lawrence Livermore National Laboratory has used their system to detect a tuberculosis surrogate, even when it is surrounded by sputum and mucus-like substances.

They also were able to differentiate between two similar bacteria, distinguishing between an avirulent strain of tuberculosis and a similar bacterium, Mycobacterium smegmatis.

Their research, using a system called Single-Particle Aerosol Mass Spectrometry, or SPAMS, is described in today's edition of Analytical Chemistry, a semi-monthly journal published by the American Chemical Society.

"Without reagents, we can rapidly detect avirulent tuberculosis that is coated in sputum-like materials and we can distinguish between two similar mycobacteria," said Kristl Adams, a LLNL postdoctoral biological physicist and the paper's lead author.

"The reason we used two similar mycobacteria in our research is that tuberculosis-like symptoms in a patient could be caused by many bacterial infections, not just tuberculosis. So we would like to differentiate between non-tuberculosis and tuberculosis infections," Adams explained.

There is no current method for screening potential tuberculosis patients within minutes," said LLNL physicist and co-author Matthias Frank, who added that the "gold standard" diagnostic tool of culturing samples can require days to weeks.

Other methods of diagnosing the disease, which each have advantages and disadvantages, are bacteria staining and counting in a sputum smear, DNA amplification using polymerase chain reaction and chest X-rays.

Without a way to rapidly screen large numbers of possible tuberculosis patients, the diagnosis of the disease can sometimes prove difficult and expensive.

In one retrospective four-month study conducted in an urban Los Angeles hospital emergency department, it was found that more than 40 percent of patients who were later found to have tuberculosis were either initially released or not isolated.

The same study also determined that resources were wasted in unneeded precautions taken for patients who, in the end, did not have tuberculosis. For every tuberculosis-positive patient, 624 patients were screened and other steps for those patients included taking 130 chest X-rays and placing 22 patients in isolation.

"It is clear," said Adams, "that a rapid tuberculosis screening technique could facilitate early detection and limit unnecessary isolation, thus providing better patient care and reducing the toll on health care facility resources."

While emphasizing that their work is only a first step toward using SPAMS for tuberculosis diagnostics, Frank and Adams said they believe SPAMS could potentially detect the disease within five minutes with concentrated samples.

Besides Adams and Frank, other researchers on the SPAMS team for this work are physicist Paul Steele, microbiologist Sue Martin, forensic chemist and graduate student Audrey Martin, former LLNL employee and physical chemist Michael Bogan and 2007 Department of Homeland Security (DHS) summer scholar Nicole Sadler.

The SPAMS researchers have spoken with doctors at two northern California university medical centers about the possibility of undertaking experiments in a clinical setting to detect virulent tuberculosis within sputum samples from infected people.

The biggest challenge going forward is determining if infectious tuberculosis in humans can be detected with our pattern-matching algorithm. It is undetermined if the virulent tuberculosis pattern will have enough similarity from patient-to-patient that we can train on a known TB patient and detect TB in a patient with an unknown infection," Adams said.

Virulent tuberculosis was estimated in 2007 to have infected about nine million people worldwide and to be fatal to 1.7 million people, according to the World Health Organization. Tuberculosis typically attacks the lungs but can infect almost any organ of the body, including the joints, bones, bone marrow, urinary tract, central nervous systems, muscles, skin and throat. It is an airborne contagious disease that spreads when a person with tuberculosis of the lungs or throat coughs, sneezes or talks.

Two sampling scenarios envisioned by the SPAMS researchers are: general room air monitoring and aerosolized patient effluent analysis.

The team also is evaluating another possible technique for diagnosing human infections — breath trace gas analysis. Trace gases exhaled in breath can hold clues about the metabolism and disease condition of a person.

Provided by Lawrence Livermore National Laboratory

Related stories:

Patient photos aid docs reading faceless CT scans
(AP) -- Imagine sitting in a dark room all day, evaluating CT scans and other medical images on a computer screen but never actually seeing real patients. That's life for many radiologists.
Researchers identify new leprosy bacterium
A new species of bacterium that causes leprosy has been identified through intensive genetic analysis of a pair of lethal infections, a research team reports in the December issue of the American Journal of Clinical Pathology.
Cellular safety shelters allow TB agent to survive in infected individuals
"Foamy" macrophage formation may be the key to persistence of infection by Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, explains a study published November 14 in the open-access journal PLoS Pathogens.
Cases of extensively drug-resistant TB declining each year in the US, but new cases still
A new report suggests that the number of cases of extensively drug-resistant tuberculosis (XDR-TB) in the U.S. has declined in the past fifteen years, but new cases continue to be reported, according to the study published in the November 12 issue of JAMA. The researchers note the decrease in the number of XDR-TB cases coincides with improved TB and HIV/AIDS control.
UCLA develops safer, more effective TB vaccine for HIV-positive people
UCLA scientists engineered a new tuberculosis (TB) vaccine specifically designed for HIV-positive people that was shown to be safer and more potent than the current TB vaccine in preclinical trials.
New TB test reveals patients at risk, says study
A recently introduced blood test can reveal which patients may develop active tuberculosis (TB) much more precisely than the 100-year old TB skin test, according to a new study published today in the journal Annals of Internal Medicine.
Researchers estimate lives lost due to delay in antiretroviral drug use for HIV/AIDS in South Africa
Boston, MA – More than 330,000 lives were lost to HIV/AIDS in South Africa from 2000 and 2005 because a feasible and timely antiretroviral (ARV) treatment program was not implemented, assert researchers from the Harvard School of Public Health (HSPH) in a study published online by the Journal of Acquired Immune Deficiency Syndromes (JAIDS) (http://www.jaids.com/). In addition, an estimated 35,000 babies were born with HIV during that same period in the country because a feasible mother-to-child transmission prophylaxis program using nevirapine (an anti-AIDS drug) was not implemented, the authors write.
Scientists discover bacteria that can cause bone infections
Scientists have discovered that a bone infection is caused by a newly described species of bacteria that is related to the tuberculosis pathogen. The discovery may help improve the diagnosis and treatment of similar infections, according to an article published in the October issue of the International Journal of Systematic and Evolutionary Microbiology.

News discussion:

General Science news