Background: Pretreatment drug resistance (PDR) poses an increasing threat to the success
of antiretroviral treatment (ART) programs in China. We aimed to conduct a survey of PDR
among HIV patients in an area in Southwest China with extensive drug trafficking.
Methods: Consecutive cross-sectional surveys were conducted in Liangshan Prefecture of Sichuan
Province from 2009 to 2018 based on the WHO-recommended method. PDR was identified by testing
pol region sequences with the Stanford HIVdb algorithm (version 7.0). PDR prevalence and related
factors were assessed by multivariable logistic regression. The transmission of HIV drug resistance
was analyzed using a genetic transmission network.
Results: HIV-1 pol genes from 1889 patients were successfully amplified. The distribution of HIV-
1 genotypes was as follows: CRF07_BC (94.0%), CRF08_BC (2.3%), CRF01_AE (2.0%) and others
(1.4%). Of the participants, 6.9% (95% CI: 4.1-8.1%) had pretreatment resistance to 12 antiretroviral
drugs recommended by the WHO, and nucleoside reverse transcriptase inhibitor (NRTI),
non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitors (PI) resistance were
identified among 1.4% (95% CI: 0.7-3.4%), 5.8% (95% CI: 1.2-8.7%) and 0.4% (95% CI: 0.1-
3.0%) of the patients, respectively. In the multivariate logistic model, the prevalence of PDR was
1.52-fold higher among intravenous drug users (IDUs) than among patients infected by heterosexual
transmission (95% CI: 1.07-2.38; P=0.049), and the prevalence of PDR among patients diagnosed
from 2017-2018 was 2.03-fold higher than that among patients diagnosed from 2009-2016 (95% CI:
1.18-5.76; P=0.018). A total of 26 clusters containing PDR and a rapidly growing drug resistancerelated
cluster containing the E138Q and V179D mutations were identified by genetic transmission
Conclusion: The results show a moderate overall level of PDR prevalence and rapidly growing
drug resistance over time. Preventive intervention should be focused on controlling the HIV epidemic
among drug users, and surveillance is urgently needed to monitor the trend of PDR.