Test for Deadly TB Glows Fluorescent

University of Pittsburgh researchers have developed a method of adding fluorescence to a bacteriophage that readily infects TB -- an innovation that could shorten time to detection.

Working with assistance from the Howard Hughes Medical Institute at the Albert Einstein College of Medicine in New York, Mariana Piuri devised a way to make TB bacteria glow. Exposing TB to antibiotics kills all bacteria not resistant to drugs, with any remaining fluorescence indicating multidrug-resistant or extensively drug-resistant TB (XDR-TB). This would allow health care providers to isolate patients with drug-resistant TB, especially to prevent transmission to HIV-infected persons whose immune systems are already compromised.

With the new procedure, sputum can be tested quickly. Such a test could be performed in 24 hours in rural African hospitals that already have laboratory tools to perform sputum smears, the researchers said.

"Clinicians need rapid, relatively cheap and simple methods for detecting TB and drug-resistant strains in the local clinic," said study co-author William R. Jacobs Jr. of the Albert Einstein College of Medicine.

The deadly co-epidemics of HIV and drug-resistant TB in Tugela Ferry in South Africa's KwaZulu-Natal province highlight "a dire and desperate need" for a new diagnostic tool, said Graham F. Hatfull, chair of the Department of Biological Sciences at University of Pittsburgh's School of Arts and Sciences. Patients coinfected with HIV and XDR TB have a median life expectancy of only 16 days and the combination of infections is almost 100 percent fatal. "This problem is more widespread than people realize," he said.

The new diagnostic tool will likely take two years before it is ready for use in the field.

The study, "Fluoromycobacteriophages for Rapid, Specific, and Sensitive Antibiotic Susceptibility Testing of Mycobacterium tuberculosis," was published online in the open-access journal Public Library of Sciences ONE (2009;4(3): e4870. doi:10.1371/journal/pone.0004870).

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