Table 1.

Expert Panel Recommendations on HIV Drug Resistance Testing

	Recommendations (EuroGuidelines Group for HIV Resistance, 2001; Hirsch et al., 2000; US Department of Health and Human Services Panel on Clinical Practices for Treatment of HIV Infection, 2000)
Primary HIV-1 infection	The DHHS and IAS-USA state that resistance testing should be considered. The more recent EuroGuidelines state that testing should be strongly considered, reflecting the increasing rates of primary HIV-1 drug resistance.
Established HIV-1 infection	Not generally recommended by any of the guidelines. Detection of drug resistance is inversely proportional to the time since infection because rates of resistance were lower in the past and because resistant strains tend to be overgrown by susceptible strains that were either co-transmitted at the time of infection or that resulted from back mutations.
First regimen failure	Resistance testing is recommended by all three panels. Patients with virologic failure while receiving drug combinations have virus isolates that are not necessarily resistant to all of the drugs in the combination and because HIV-1 may develop drug resistance by more than one mechanism and each mechanism may have different consequences for cross-resistance.
Suboptimal viral suppression after initiation of HAART	Recommended by DHHS. Not specifically recommended by the IAS-USA and EuroGuidelines committees but probably falls under the “First regimen failure” category.
Multiple regimen failures	Recommend testing to optimize the number of active drugs in the next regimen; exclude drugs to which response is unlikely.
Pregnancy	Recommend testing to optimize maternal treatment and prophylaxis for neonate.
Post-exposure prophylaxis	Addressed by EuroGuidelines which recommends testing but cautions that treatment should not be delayed while waiting for the test result. Rather, the results of the test should be used to modify the treatment.