Similar tests are used to test for bacterial resistance before treatment with antibiotics. A phenotypic test usually requires a blood sample from someone with a viral load over 1,000. Also, the results take 4-6 weeks to come through. Drugs are not usually tested in combinations. Since there are so many possible combinations of drugs, this would be very expensive and time-consuming.
Many labs offer genotypic testing.
Phenotypic testing is less widely available. The table below shows labs offering resistance tests. They may not all be as reliable in their ability to provide good results. They differ in quality control, test sensitivity and the accuracy and interpretation of results. However, with growing evidence of their value, more insurance companies and other third-party payers are willing to pay for them.