The growing prevalence of drug-resistant tuberculosis is a "potentially explosive situation," the World Health Organization's director general, Margaret Chan, said today at the opening of a three-day meeting on the problem.

Representatives from 27 countries affected by multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are gathering in Beijing to discuss how to address the trend. MDR-TB is resistant to first-line drugs; XDR-TB doesn’t respond to those meds or second-line therapies. More than 500,000 MDR-TB cases occur annually—only 3 percent of them treated according to WHO standards—and XDR-TB exists in more than 50 countries, the agency says. People with HIV, whose immune systems are already weakened by the AIDS-causing virus, are at increased risk of TB.

"Call it what you may—a time bomb or a powder keg," Chan said today, according to the Associated Press. "Any way you look at it, this is a potentially explosive situation."

The countries participating in the talks are expected to commit themselves to scale up their TB diagnosis and treatment programs. Country reps attending the meeting are from Armenia, Azerbaijan, Bangladesh, Belarus, Bulgaria, China, Democratic Republic of Congo, Estonia, Ethiopia, Georgia, India, Indonesia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Republic of Moldova, Myanmar, Nigeria, Philippines, Russian Federation, Pakistan, South Africa, Tajikistan, Ukraine, Uzbekistan and Vietnam.

The field got a boost in February when scientists reported that previously dismissed antibiotics killed 13 strains of drug-resistant TB in the lab. Clinical trials of the drug combination are in the works.

Our in-depth report on multidrug-resistant TB sheds additional light on the infection.

Leo Vincant Jawili carries his wife, Decere Lai Jawili, to a taxi outside the International Center for Tuberculosis in Manila, Philippines, where she receives daily treatment for MDR-TB/WHO, Dominic Chavez