Drug Resistance Testing
ÎInitial drug resistance testing is recommended for all persons with HIV infection (AIII). If therapy is deferred, repeat testing at the time of ART initiation should be considered (CIII).
ÎA genotypic assay is generally preferred for ARV-naïve persons (AIII). If transmitted integrase strand transfer inhibitor (INSTI) resistance is a concern, providers may wish to supplement standard genotypic resistance testing with genotypic testing for resistance to this class of drugs (CIII).
ÎPerform drug resistance testing to select active drugs when changing ARV regimens in cases of virologic failure and HIV RNA levels > 1,000 copies/mL (AII). Consider testing in persons with > 500 but < 1,000 copies/mL (BII).
ÎGenotypic testing is the preferred resistance testing to guide therapy in patients with suboptimal virologic responses or virologic failure while on first or second regimens (AIII).
ÎAddition of phenotypic testing to genotypic testing is generally preferred for persons with known or suspected complex drug resistance mutation patterns, particularly to protease inhibitors (BIII).
ÎPerform drug resistance testing in the setting of virologic failure while the patient is taking ARV drugs, or within 4 weeks after discontinuing therapy (AII).
ÎPerform genotypic resistance testing for all pregnant women prior to initiation of therapy (AIII) and for those entering pregnancy with detectable HIV RNA levels while on therapy (AII).
ÎIn persons failing INSTI-based regimens, genotypic testing for INSTI resistance should be considered to determine whether to include a drug from this class in subsequent regimens (BIII).
HLA-B*5701 Screening
ÎScreen for HLA-B*5701 before starting patients on an abacavir- containing regimen, to reduce the risk of hypersensitivity reaction (AI).
ÎHLA-B*5701-positive patients should NOT be prescribed abacavir (AI). The positive status should be recorded as an abacavir allergy in the patient's medical record (AII).
ÎWhen HLA-B*5701 screening is not readily available, initiate abacavir with appropriate clinical counseling and monitoring for any signs of hypersensitivity reaction (CIII).
Coreceptor Tropism Assays
ÎPerform coreceptor tropism assay whenever the use of a CCR5 inhibitor is being considered (AI).
ÎConsider coreceptor tropism testing for patients who exhibit virologic failure on a CCR5 inhibitor (CIII).
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