Researchers are perplexed following the discovery that
tuberculosis may not be completely gone in those who are deemed “cured.” A
recent study found evidence of the bacterium that causes TB remains in the
lungs after treatment. A study of 99 HIV-negative individuals in Cape Town, South
Africa, who had been treated for pulmonary tuberculosis with a rigorous
antibiotic regimen, had their lungs imaged before during and after treatment. Investigators at Stellenbosch University used a CT scan, a
more detailed form of x-ray, and PET scans that glow bright to reveal the
presence of lung abnormalities.
Imaging in 76 of those patients thought to be cured showed
continued inflammation in the lungs and lesions similar to those of untreated
patients. One year after treatment, 50 patients showed similar lung
involvement, although most of the lesions had decreased in size. Sixteen
patients with some abnormalities picked up in the scans were otherwise free of
lesions.
Researchers also detected genetic material in the saliva and
mucus of 34 patients, an indication that live bacteria remained in their lungs. “Oh yeah, we certainly were,” said Clifton Barry describing
the surprised reaction of researchers. Barry is a senior scientist at the U.S. National Institutes
of Health Tuberculosis Research Section. He co-authored the study published in the journal Nature
Medicine. “We were quite surprised to see the residual findings at the
end of treatment... and the evidence of presence of active live bacteria in
patients we called cured of tuberculosis,” Barry added.
Barry said investigators don’t know what the implications
are, but they wonder whether such patients could relapse and, if so, whether a
second infection could become resistant to antibiotics.
A six-month course of antibiotics has been the gold standard
in treating patients, who afterwards usually show no symptoms of TB. Said Barry, “I think the question is, “Is that really
enough?” And do we need to think about potentially looking more carefully at
patients at the end of treatment and evaluating in a different algorithm how we
treat individual patients.” One-third of the world’s population is infected with
tuberculosis.
The U.S. Centers for Disease Control and Prevention says 9.5
million people become sick and 1.5 million die. Not only might TB patients need to be monitored closely
after treatment, researchers say the study points up that new strategies may be
needed for dealing with tuberculosis. These may include doing genetics tests to determine the
bacterium’s genotype, or severity and traits, so treatment regimens may be
tailored to individuals infected with TB, replacing a one-size fits all
approach to curing tuberculosis.
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