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human immunodeficiency virus (HIV) changes (mutates)
often. Sometimes these changes make the virus resistant to a particular
medicine or class of medicines, which means the medicine is no longer effective
against the virus. When this happens, the medicine no longer controls virus
growth (replication) or protects the
Resistance testing is done to determine whether
resistance has caused treatment to fail and to identify antiretroviral
medicines that can be used to treat the infection. There are many reasons that
treatment fails, such as:
Two tests are available to detect resistance to medicines
used to treat HIV infections:
Both of these tests are done on a sample of blood taken from
a vein. These tests may not be accurate if the resistant virus is less than 20%
of the circulating virus.
You may be tested for infection with a
resistant virus when:
Resistance reduces the number of treatment options in the future, so it is important to keep resistance from happening.
Current as of:
June 4, 2014
E. Gregory Thompson, MD - Internal Medicine & Peter Shalit, MD, PhD - Internal Medicine
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