The Test Sample
What is being tested?
Resistance is a term used to describe the condition in which a microorganism is able to grow and/or multiply in the presence of one or more antimicrobial drugs. Human immunodeficiency virus (HIV) genotypic resistance testing evaluates the likelihood that the HIV strain infecting an individual has developed resistance to drug treatment.
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, 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. 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 or changes that are known to cause anti-retroviral (ARV) drug resistance.
To avoid the development of ARV resistance, it is usually recommended that a person with HIV be treated with a combination of drugs that are from two different classes of ARV. This is known as highly active retroviral therapy or HAART. There are many different ARVs approved by the U.S. Food and Drug Administration that fall into different categories. For more on this, visit the National Institute of Allergy and Infectious Diseases web page on Treatment of HIV Infections.
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.