Shorter antibiotic course for latent TB increases compliance

An antibiotic regimen four months long results in more patients with latent tuberculosis taking all their pills than does the more common nine-month approach, according to a study in a November Annals of Internal Medicine (link). Trials with more participants now are needed to determine if this shorter course is as effective at eradicating the bacteria.

"It's about just trying to get people to finish treatment," said Dr. Dick Menzies, lead author and director of the respiratory division at McGill University in Montreal. "If you prescribe an antibiotic for a week, a lot of people don't finish. When I tell people they need nine months, their face falls and they're looking around trying to get away. It seems impossible."

Researchers randomized 847 latent TB patients in Canada, Brazil and Saudi Arabia to either four months of daily rifampin or nine months of daily isoniazid. Both medicines were taken daily and are guideline-recommended regimens, although the longer course is preferred. Of the 422 patients randomized to isoniazid, 17 developed serious adverse events, compared with seven of the 418 on rifampin. Also, 60% of those taking isoniazid completed treatment, while 78% on rifampin finished the course.

Experts say the data indicate the need to determine if the shorter regimen works as well as longer ones in eradicating this infection, and the study authors are now seeking funding to do so. They also are analyzing how the two regimens compare on cost.

Scientists have long hunted for antibiotic regimens that are easier to take, because evidence suggests that fewer than half of patients comply with latent TB treatment. The hope is that shorter regimens with fewer adverse events will make it more likely that the course will be completed and that the spread of this infection, which already has decreased significantly, will diminish further.

According to an October Centers for Disease Control and Prevention tuberculosis report, the rate of active TB was 4.4 per 100,000 in 2007 -- the lowest rate since 1953, when reporting began (link). The agency also is running its own trial comparing three months of weekly rifapentine combined with daily isoniazid to nine months of daily isoniazid by itself. Those results are expected in 2010.

The American Medical Association supports legislation leading to increased resources for TB control in the U.S. and abroad.