Objective To investigate the distribution characteristics of HIV-1 subtypes,the status of transmitted drug resistance(TDR),and the influencing factors of TDR in treatment-naive patients with AIDS who are hospitalized.Methods Treatment-naive patients with AIDS who were admitted to the Infectious Disease Department,Public Health Clinical Center of Chengdu between January 2020 and December 2022 were enrolled in the study.The diagnosis and confirmation diagnosis of all the subjects were made at the same hospital.Blood samples were collected from the subjects before antiretroviral therapy(ART).The in-house method was used for HIV gene amplification and sequencing.A phylogenetic tree was constructed to analyze the HIV-1 subtypes.The Stanford HIV Drug Resistance Database was used to conduct an online comparative analysis of the drug resistance mutation sites and to determine the types and levels of drug resistance.The distribution characteristics of HIV-1 subtypes,the occurrence of TDR,and the influencing factors of TDR were analyzed.Results A total of 213 patients were included in the study and their blood samples were collected.HIV-1 subtypes were successfully amplified in 83.10％(177/213)of the subjects.Ten HIV subtypes were identified,with CRF07_BC being the most common subtypes,accounting for 43.50％(77/177),which was followed by CRF01_AE at 37.85％.Unique recombinant forms(URFs)were relatively uncommon,accounting for 8.47％.The other subtypes accounted for 10.17％.These 4 categories of HIV-1 subtypes were distributed with statistically significant differences in different age groups(P=0.024).Further analysis revealed significant differences in the distribution of the HIV-1 subtypes of CRF01_AE and URFs between the groups of patients aged 30-50 years and those over 50.In addition,URFs accounted for a higher proportion in patients aged 30 to 50 years(P=0.008).The incidences of TDR were 6.49％,8.96％,13.33％,and 5.56％for CRF07_BC,CRF01_AE,URFs,and other subtypes,respectively,showing no significant difference(P＞0.05).The overall TDR was 6.57％.The TDR for non-nucleoside reverse transcriptase inhibitors(NNRTIs)was 5.16％,and the main mutation sites were V179D/E,E138A/G,V106M/I,and Y181C.The TDR for nucleoside reverse transcriptase inhibitors(NRTIs)was 1.88％,and the main mutation site was M184V.One patient was found to be resistant to both NNRTIs and NRTIs.The highly resistant rate was 4.23％,moderate resistance was 0.47％,and low resistance was 1.88％.No significant effects of the specific years,demographic characteristics,transmission route,baseline condition,and opportunistic infections on TDR were found in this study(P＞0.05).Conclusions The HIV-1 subtypes are diverse and complex in treatment-naive patients with AIDS who were hospitalized.The overall prevalence of TDR is relatively high.It is necessary to strengthen HIV drug resistance testing to optimize ART treatment and reduce the risk of drug resistance transmission.