Study finds more AIDS cases that resist drug mixes

BARCELONA, Spain -- More Americans are getting infected with forms of HIV that are resistant to life-extending drugs, a finding produced by a study showing that 16 percent of new cases in San Francisco are caused by a strain that resists treatment with one or more drugs.

An analysis of the viruses found in 225 newly infected individuals between June 1996 and June 2001 revealed a steady upward trend in drug resistance, according to a University of California at San Francisco study to be published in the Journal of the American Medical Association. It was released here in advance of the 14th International AIDS Conference, set to convene today.

The findings cast a doubt on how long the drug cocktails that have revolutionized HIV treatment in the United States and Europe will continue to work.

According to Dr. Robert Grant and his colleagues at the university, about 20 percent of newly infected San Franciscans carry forms of the virus that are highly resistant to one of the three classes of anti-HIV drugs. Thirteen percent are infected with forms that are resistant to two classes. And 1.2 percent are resistant to all available classes of the drugs.

They also found that patients with viruses resistant to some drugs required three times longer for the remaining available drugs to be effective in reducing the level of virus in the bloodstream. The finding also hampers the routine of changing a patient's medications to prevent side effects and toxicity buildup.

More stringent tests

Drug-resistant forms of HIV aren't new. Last fall, Dr. Douglas Richman of the University of California, San Diego showed that more than 70 percent of Americans on medication for three or more years carry drug-resistant strains. And high rates of resistance had previously been seen in new cases, but those studies used far less stringent standards. The new study counted only viruses that could tolerate doses of drugs that were 10 times the norm. By that measure, these are indeed serious findings, Grant said, and should alarm clinicians nationwide.

The appearance of drug-resistance strains in new diagnoses is being attributed to the spread of the virus via unprotected sex. In an interview, Grant raised questions about the need to link treatment with prevention education in an effort to decrease the likelihood that individuals infected with drug-resistant viruses will pass them on to their partners.

"Do we require smokers to quit if they are treated for chronic bronchitis or asthma in public programs? No," Grant said. "Do we require alcoholics to stop drinking in order to receive treatment for complications of ethanol abuse? No. Are persons injured in sports required to pay for their own care? No. Quid pro quo is not appropriate for HIV infection either.

"Nonetheless, I think that infected persons, whether treated or not, should protect their partners because of a social obligation to the welfare of others, especially lovers."

Grant noted, however, that many physicians haven't found effective ways to talk to their HIV patients about prevention.

The most disturbing results were found with one class of drugs, non-nucleoside reverse transcriptase inhibitors, or nnRTIs. In 1996 none of the primary infections studied involved viruses that could resist those drugs. But by mid-2001, the viruses found in 13.2 percent of newly infected San Franciscans were resistant.