MARCH 23, 2009--Latest in a recent series of announcements about rapid tuberculosis (TB) detection and TB bacteria containment (spread reduction), researchers from the University of Pittsburgh (Pittsburgh, PA) and the Albert Einstein College of Medicine (Bronx, NY) say they have developed a fluorescent method for on-site diagnosis of TB and exposure of the deadly drug-resistant strains of Mycobacterium TB that can mingle with treatable strains. The group's research was funded as part of a major new research initiative from Howard Hughes Medical Institute (HHMI) focused on TB and HIV research.
The method must next undergo clinical trials, but it has potential as a valuable, timesaving tool in rural African areas besieged by TB, says Graham Hatfull, senior author of a report describing the discovery, published in the journal PLoS ONE. Hatfull, who is chair and Eberly Family Professor of Biological Sciences in Pitt's School of Arts and Sciences, conducted the research with Prof. William Jacobs Jr. of the Department of Microbiology and Immunology at the Albert Einstein College of Medicine of Yeshiva University (New York, NY) and Pitt postdoctoral fellow Mariana Piuri.
"A report from South Africa showed that the extensively drug-resistant TB strains can kill within 16 days, on average," Hatfull said. "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."
The group constructed bacteriophages specific to TB that have 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. A clinician can detect the GFP's glow with equipment available at many clinics.
Besides quick diagnosis, the test also could be used to distinguish treatable TB strains from those that are drug resistant, a chore that can normally take months, Hatfull said. Hatfull and his colleagues 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.
The work was funded as part of a major new research initiative from Howard Hughes Medical Institute (HHMI) announced March 19. The institute will partner with South Africa's University of KwaZulu-Natal to establish an international research center focused on the TB and HIV coepidemics in Africa, called KwaZulu-Natal Research Institute for TB-HIV. Jacobs will direct research into developing rapid and effective TB tests, one of the new institute's primary objectives. His work with Hatfull and Piuri was related to that effort.
"The development of reporter flurophages," Jacobs said, "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."
For more information see the PLoS ONE paper, Fluoromycobacteriophages for Rapid, Specific, and Sensitive Antibiotic Susceptibility Testing of Mycobacterium tuberculosis, on Pitt's website. For further details about the the TB/HIV initiative see the HHMI Web site.