Survey finds wide resistance to TB drugs.

It's been said that people are smart but bacteria are smarter.

That adage is bolstered by a new study revealing that the tuberculosis bacterium has developed widespread resistance to the most commonly used anti-tuberculosis drugs, outwitting human-made antibiotics at least some of the time in all 35 countries sampled.

The 4-year study, led by the World Health Organization, shows that of people who had been treated for tuberculosis for less than a month, 36 percent harbored microbes that resisted at least one of the four main anti-tuberculosis drugs. Moreover, 10 percent of infected people who had never been treated for the disease carried a strain of Mycobacterium tuberculosis that resisted at least one drug, researchers report in the June 4 New England Journal of Medicine. Resistance to more than one drug showed up in 13 percent of the treated people and in 1.4 percent of untreated people.

Although few patients were resistant to all four drugs, the findings suggest great risk, says Leonid Heifets of the National Jewish Medical and Research Center in Denver.

Doctors usually treat the disease with all four main drugs for 2 months, then continue with two of them for 4 more months, Heifets says. Many patients, however, don't take medication long enough to knock out the bacteria. "People feel better after a month of treatment" and stop taking the pills, says study coauthor Ariel Pablos-Mendez of Columbia University. Meanwhile, bacteria that mutated in the presence of the drugs may survive when treatment is interrupted. When patients suffer a relapse, they unleash mutated bacteria that are resistant to one or more of the drugs.

This study suggests that many people develop resistant microbes during the last 4 months of treatment and are incompletely cured after 6 months, Heifets says.

Heifets calls the study "a very impressive undertaking.... It's an eye-opener."

The researchers examined dates from more than 45,000 people with tuberculosis in Europe, Africa, the Americas, the Western Pacific, and Southeast Asia. Resistance proved strongest in Latvia, Estonia, Sierra Leone, the Dominican Republic, Argentina, Thailand, Bolivia, Vietnam, and a region of Russia east of Moscow.