Antiretroviral drugs are used to treat people infected with HIV, the virus that causes AIDS.
"The problem with drug resistance is that once you develop it, it never goes away," study author Dr. Russell Van Dyke, a professor of pediatric infectious diseases at Tulane University School of Medicine, said in a university news release.
"Some patients with very resistant virus have no effective treatment options. Resistant virus is the major reason for death among youth" who were born with HIV, he added.
The study looked at 450 HIV-infected children across the United States and found that 74 percent were resistant to at least one type of HIV drug, and 30 percent were resistant to two classes of drugs. By comparison, the rates in HIV-infected adults were 36 percent and 12 percent, respectively.
Fortunately, most HIV-infected youngsters with treatment-resistance still respond to newer medicines in all drug classes. Only one child in the study was resistant to all HIV drugs. Just under 20 percent were resistant to one drug from each of the three main classes of HIV medications, according to the study.
The findings highlight the importance for HIV-infected youngsters to take the required multiple daily medications. Once-a-day, single-pill HIV drugs are available for adults but not for children, the study authors noted in the news release.
"The best way to prevent resistance from developing is to take your medicine and suppress your viral load," Van Dyke said. "You develop resistance when you take some of your medications but not all. Then you've got virus that is replicating in the face of taking your medication. Lack of adherence is the major reason resistance develops."
The study was presented at the recent Conference on Retroviruses and Opportunistic Infections in Boston. Research presented at meetings should be considered preliminary until published in a peer-reviewed journal.
The U.S. National Library of Medicine has more about HIV/AIDS medicines.