FrontLines: What Is Multiple-Drug Resistant TB?

March 2004

When tuberculosis (TB) patients don’t take their medication consistently and for long enough, resistance to the drugs can develop.

Drug-resistant TB is common in countries such as the former Soviet Union, Israel, and South Africa, where “first line” drugs against TB were extensively used but not taken as prescribed.

In Eastern Europe and Central Asia, drug-resistant TB is 10 times more prevalent than elsewhere.

The cost of drug-resistant TB is high, both to the individual patient and society. While first-line drugs used to treat a simple case cost about $10, “second line” drugs to treat multiple-drug resistant TB (MDR-TB) are up to 100 times more expensive. They also have no guarantee of success.

In addition, testing for and treating MDR-TB requires a more sophisticated medical infrastructure, including well-equipped laboratories, skilled technicians, and specialized doctors. For instance, if a patient has a drug-resistant strain, lab technicians need to run tests to identify the drugs the strain resists. Treatment is then tailored to the strain with a combination of other drugs. Physicians must closely monitor the patient’s reaction, since this combination can be more toxic than first-line drugs.

Global medical experts fear that TB will develop resistant strains faster than new TB drugs can be developed. As the World Health Organization (WHO) reported March 17, 79 percent of MDRTB cases do not respond to three of the four most common drugs that have been used.

WHO has developed new guidelines for treating MDR-TB, but it advocates an expansion and strict adherence to the cur-rent TB treatment—directly observed treatment, short-course or DOTS—to keep the spread of MDR-TB at bay, said Irene Koek, USAID’s division chief for infectious diseases in the Bureau for Global Health.

DOTS helps prevent MDR-TB because medical personnel watch patients to ensure they take their daily medication and finish the six-month regimen.

Another DOTS principle is to examine sputum under a microscope to detect TB. Other tests, such as lung x-rays, are more expensive, less specific, and potentially harmful to patients. In the former Soviet Union, x-ray tests were commonly used to detect the disease.

In the United States, the Centers for Disease Control and Prevention (CDC) reported March 18 that foreign-born TB patients are twice as likely to suffer from MDR-TB than patients born in the United States. Foreign-born residents generally account for more than half of all TB cases in the United States.


Access the March 2004 edition of FrontLines [PDF, 2MB].