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The Test Sample
What is being tested?
Human immunodeficiency virus (HIV) genotypic antiretroviral drug resistance testing evaluates the likelihood that the HIV strain infecting an individual is resistant or has developed resistance to one or more antiretroviral therapy (ART) drugs. The test analyzes the genes of the HIV strain infecting the person to identify mutations that may cause the virus to be resistant to ART. Someone may be initially infected with a drug-resistant HIV strain or drug resistance may develop during treatment.
In general, drug resistance describes the condition in which a microorganism is able to survive, grow and/or multiply in the presence of one or more antimicrobial drugs. Resistance can develop when antimicrobials are used to treat an infection and a mutation or change occurs in one of the microorganism's genes. This change leads to a mixed population in the infected person's body – some microorganisms that are drug-resistant and some that are drug-sensitive. Microorganisms without the mutation are killed, but those that have the mutation quickly multiply and begin to predominate. This is called "selective pressure" because the drug "selects" and allows the proliferation of the genetic forms of the microorganism that are resistant to it. When this occurs, the antimicrobial is no longer effective in treating the infection.
HIV mutates frequently – even in the absence of drug treatment – but not every mutation causes resistance to antiretroviral drugs. With genotypic resistance testing, the genetic code of the HIV a person has been infected with is analyzed to determine if there are any genetic mutations that are known to cause ART resistance.
To avoid the development of ART resistance, it is recommended that individuals with HIV be treated with a combination of drugs that are from two different classes of antiretroviral drugs. This is known as highly active antiretroviral therapy or HAART. There are many different antiretroviral drugs approved by the U.S. Food and Drug Administration. For more on this, visit the National Institute of Allergy and Infectious Diseases web page on Treatment of HIV Infection. Photo source: National Institute on Allergy and Infectious Diseases
How is the sample collected for testing?
The test is performed on a sample of blood drawn from a needle placed in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.