title: Emergence of HIV-1 drug resistance mutations among antiretroviral-naïve HIV-1-infected patients after rapid scaling up of antiretroviral therapy in Thailand.
abstract: BACKGROUND
  After rapid scaling up of antiretroviral therapy in HIV-1-infected patients, the data of primary HIV-1 drug resistance in Thailand is still limited. This study aims to determine the prevalence and associated factors of primary HIV-1 drug resistance in Thailand.
  
  
  METHODS
  A prospective observational study was conducted among antiretroviral-naïve HIV-1-infected Thai patients from 2007 to 2010. HIV-1 subtypes and mutations were assayed by sequencing a region of HIV-1 pol gene. Surveillance drug resistance mutations recommended by the World Health Organization for surveillance of transmitted HIV-1 drug resistance in 2009 were used in all analyses. Primary HIV-1 drug resistance was defined as the presence of one or more surveillance drug resistance mutations.
  
  
  RESULTS
  Of 466 patients with a mean age of 38.8 years, 58.6% were males. Risks of HIV-1 infection included heterosexual (77.7%), homosexual (16.7%), and intravenous drug use (5.6%). Median (IQR) CD4 cell count and HIV-1 RNA were 176 (42-317) cells/mm(3) and 68,600 (19,515-220,330) copies/mL, respectively. HIV-1 subtypes were CRF01_AE (86.9%), B (8.6) and other recombinants (4.5%). The prevalence of primary HIV-1 drug resistance was 4.9%; most of these (73.9%) had surveillance drug resistance mutations to only one class of antiretroviral drugs. The prevalence of patients with NRTI, NNRTI, and PI surveillance drug resistance mutations was 1.9%, 2.8% and 1.7%, respectively. From logistic regression analysis, there was no factor significantly associated with primary HIV-1 drug resistance. There was a trend toward higher prevalence in females [odds ratio 2.18; 95% confidence interval 0.896-5.304; p = 0.086].
  
  
  CONCLUSIONS
  There is a significant emergence of primary HIV-1 drug resistance in Thailand after rapid scaling up of antiretroviral therapy. Although HIV-1 genotyping prior to antiretroviral therapy initiation is not routinely recommended in Thailand, our results raise concerns about the risk of early treatment failure in patients with primary HIV-1 drug resistance. Interventions to prevent the transmission of HIV-1 drug resistance and continuation of surveillance for primary HIV-1 drug resistance in Thailand are indicated.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. somnuek.sun@mahidol.ac.th
authors.forename: Somnuek
authors.initials: S
authors.lastname: Sungkanuparph
authors.forename: Chonlaphat
authors.initials: C
authors.lastname: Sukasem
authors.forename: Sasisopin
authors.initials: S
authors.lastname: Kiertiburanakul
authors.forename: Ekawat
authors.initials: E
authors.lastname: Pasomsub
authors.forename: Wasun
authors.initials: W
authors.lastname: Chantratita
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D003430:Cross-Sectional Studies; D024882:Drug Resistance, Viral; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D015995:Prevalence; D011446:Prospective Studies; D013785:Thailand; D055815:Young Adult
chemical_list: D019380:Anti-HIV Agents