HIV-1 drug resistance in Thailand: before and after National Access to Antiretroviral Program.

Background: The Ministry of Public Health (Thailand), MoPH, has had a program called National Access to Antiretroviral Program for People who have AIDS (PHA) or "NAPHA", to offer free antiretroviral drugs (ARV), which are locally produced in Thailand, to any HIV-1 infected patients with CD4<200 since 2002. This program may increase usage of ARV therapy and the emergence of HIV-1 drug resistance.

Objectives: To monitor HIV-1 ARV drug resistant codon mutation in Thailand before and after the "NAPHA" program.

Materials And Methods: EDTA blood samples were collected from 542 HIV-1 infected subjects, who received ARV therapy in 1999 and 2001-2003, and perinatal chemoprophylaxis in 1998 and 2000. HIV-1 pol nucleotide sequences were analyzed.

Results: The percentage of drug resistant detection from the ARV therapy group in 1999 and 2001-2003 were 12.14 (34/280), 10.23 (9/88), 86.96 (20/23) and 57.55 (61/106), respectively. Of 332 NRTI drug resistant codon mutation, 226 (68.07%) were thymidine analogue mutations (TAMs). The percentage of TAMs detection in 1999 and 2001-2003 were 7.14 (20/280), 9.09 (8/88), 56.52 (13/23) and 43.34 (46/106), respectively. Of 105 NNRTI drug resistant codon mutation, 95 (90.48%) were related to nevirapine drug resistance.

Conclusion: Thailand may need more appropriate monitoring of drug resistance in the free ARV therapy program to protect the future usage of drugs by minimizing the emergence of drug resistance.