Researchers from the University of Pittsburgh and the Albert Einstein College of Medicine have developed a simple onsite technique to quickly diagnose tuberculosis (TB)- injecting strains of Mycobacterium tuberculosis with fluorescent-green protein.
The new technique can expose the deadly drug-resistant strains of Mycobacterium tuberculosis that can mingle undetected with treatable strains.
Thus, the researchers engineered bacteriophages-tiny viruses that attack bacteria-to inject TB bacteria with a glowing, fluorescent-green protein.
Senior author Graham Hatfull, chair and Eberly Family Professor of Biological Sciences in Pitt's School of Arts and Sciences, said that the method must next undergo clinical trials, but it had potential as a valuable, timesaving tool in rural African areas plagued by TB.
"A report from South Africa showed that the extensively drug-resistant TB strains can kill within 16 days, on average. In rural Africa, it takes too long to collect samples, send them off, do the test, and have the data sent back. Clinicians need rapid, relatively cheap, and simple methods for detecting TB and drug-resistant strains at the local clinic. This test provides a quick diagnosis so the patient can be isolated and treated," said Hatfull.
The researchers constructed bacteriophages specific to TB that had a green fluorescence protein (GFP) implanted in their genome.
Bacteriophages spread by injecting their DNA into bacterial cells-in this case the GFP gene accompanies the DNA into the TB cell, causing the cell to glow.
Then, a clinician can detect the GFP's glow by using equipment available at many clinics.
Hatfull said that other than quick diagnosis, the test could also be used to distinguish treatable TB strains from those drug resistant, something that can normally take months.
The researchers treated M. tuberculosis with antibiotics at the same time the bacteriophages were introduced, and found that the TB strains that were sensitive to antibiotics died, but the drug-resistant cells survived and continued to glow.
"The development of reporter flurophages allows us to bypass the existing method of diagnosing TB, which requires cultivating slow-growing bacteria in a biosafety level 3 environment, a time-consuming and costly process. By infecting live M. tuberculosis cells with a flurophage, a quick and highly sensitive visual reading can be done. We are optimistic that we can move the diagnostic process from several weeks to several days or even hours, which could have a significant impact on treatment," said one of the authors of the study.
The study has been published in PLoS ONE, a peer-reviewed online journal from the Public Library of Science.