New TB Test Will Dramatically Cut Diagnosis Time

An onsite method was developed to quickly diagnose tuberculosis (TB) and expose the deadly drug-resistant strains that can mingle undetected with treatable TB strains.

The gene for green fluorescence protein (GFP) was implanted in the genome of bacteriophages, tiny viruses that attack bacteria. Bacteriophages inject their DNA into bacterial cells in order to multiply. The GFP gene accompanies the DNA of the phage into the Mycobacterium tuberculosis cell, the bacterium that causes TB, causing the cell to glow. A clinician can detect the glow with equipment available at many clinics.

The test was also used to distinguish treatable TB strains from those that are drug resistant (DR-TB) and extensively drug resistant (XDR-TB), which normally takes months. The scientists treated M. tuberculosis with antibiotics at the same time the bacteriophages were introduced; the TB strains that were sensitive to antibiotics died, but the drug-resistant cells survived and continued to glow.

Scientists from the Albert Einstein College of Medicine (Bronx, NY, USA) and The University of Pittsburgh (Pittsburg, PA, USA) developed the rapid diagnostic method for TB. "The development of these 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," said William R. Jacobs, Jr., Ph.D., one of the team that developed the test. "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."

The study appeared in the March 19, 2009 edition of PLoS ONE.

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Albert Einstein College of Medicine
The University of Pittsburgh