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Study: AIDS Virus Increasingly Resistant to Many Drugs - 2002-07-07

A new U.S. study shows that resistance is spreading to the most powerful drugs used to treat the AIDS virus.

San Francisco doctors report in the Journal of the American Medical Association that they have found HIV to be increasingly resistant to several classes of AIDS drugs.

By examining genetic mutations in the virus from 225 HIV patients, they found the biggest increase in resistance has been against the oldest group of drugs, which are the most common type used in developing nations. One of the researchers, San Francisco General Hospital's Dr. Frederick Hecht, says his team also detected resistance to newer classes of AIDS drugs, but to a much smaller degree. "We're seeing in recent transmission of HIV that there is an increase in HIV resistant to our most potent classes of drugs," he said. "We're also seeing increases in transmission of HIV that is resistant to two or more classes of HIV drugs."

The study shows that the number of gene mutations associated with resistance to the older class of AIDS drugs rose in the study population from none in 1996 to 13 percent five years later. In a new class of therapies, it increased from 2.5 percent to nearly 8 percent.

Dr. Hecht says the study looked at too few patients to determine the potential for epidemic spread of drug resistant HIV. But he told reporters at the International AIDS Conference that the results should be a warning to those who engage in risky sexual behavior. "Some people are becoming infected with virus that is going to be not impossible but much more difficult to treat," said Dr. Hecht. "Therefore, this assumption that getting HIV infection today is essentially a relatively easy thing to treat may not apply, especially if these trends continue."

Dr. Hecht says the results suggest that patients in areas where HIV rates are high should be tested for drug resistance.