ATLANTA -- Health officials said yesterday that they are seeing what appears to be a disturbing increase around the world in tuberculosis infections that are resistant to both the first- and second-line antibiotics that are used against the disease.
''It's basically a death sentence. If people are failing first- and second-line drugs and we don't have in the pipeline a new drug for immediate use, that's a crisis," said Dr. Marcos Espinale, executive secretary of the World Health Organization's Stop TB Partnership.
The Centers for Disease Control and Prevention and the World Health Organization surveyed a network of 25 tuberculosis laboratories on six continents from 2000 to 2004 and found that 1 in 50 TB cases around the world is resistant not only to the usual first-choice treatments, but also to many medications that represent the second line of defense.
The survey represented the first international data on what is being called ''extensively drug-resistant" TB.
For more than a decade, health officials have voiced concern about ''multidrug-resistant" TB, which can withstand the mainline antibiotics isoniazid and rifampin. One in five TB cases falls into that category, according to the survey.
But the survey also found many cases of a more difficult form of TB -- one that does not respond to at least three of six classes of second-line drugs.
That is especially worrisome, because second-line drugs are generally considered more toxic and less effective. ''These are individuals who are virtually untreatable with available drugs," said Dr. Kenneth Castro of the CDC.
The survey looked at 17,690 TB cases analyzed for drug susceptibility. Of those, 20 percent were multidrug-resistant and 2 percent were extensively drug-resistant.
The problem was worst in Latvia, where public healthcare deteriorated after the Soviet Union collapsed. Doctors say TB develops resistance to drugs because some patients fail to complete a full course of medication.
In the United States, health officials looked at 169,654 TB cases from 1993 to 2004 that were analyzed for their response to drug therapy.
The findings were that 1.6 percent were multidrug-resistant and 0.04 percent were extensively drug-resistant. US multidrug-resistant cases rose from 2003 to 2004, from 113 to 128. The number represented the largest single-year increase in more than 10 years. Ninety-seven of 128 cases were reported in people born in other countries, mostly Mexico, the Philippines, and Vietnam.
Overall, the TB rate in the United States has never been lower. In 2005, about 14,100 cases were reported, or 4.8 cases per 100,000 people. That is a 4 percent decline in the rate from 2004; however, the TB rate in foreign-born people in the United States was 8.7 times that of US natives.
''Worsening resistance around the world poses a problem in the US," Castro said.