Objective To investigate the genotype distribution and drug resistance of hepatitis C virus (HCV) among intravenous drug users (IDUs) in Guangzhou. Methods Plasma samples were collected from 99 IDUs diagnosed with HCV infection between August 2023 and January 2024. RNA was extracted, and the non-structural protein 5B (NS5B) region was amplified and sequenced. Phylogenetic trees were constructed via the maximum likelihood method in MEGA11.0.13 software, and the sequences were uploaded to the HCV resistance surveillance database for drug resistance site analysis.

Results Among the 99 HCV-infected IDUs, 86 were male and 13 were female, with 89.89% (89) of the cases aged over 50 years. A total of 96 NS5B sequences were obtained, revealing four genotypes: 6a, 3a, 1b, and 3b, which accounted for 45.83%, 30.21%, 20.83%, and 3.13%, respectively. The distribution of the four genotypes showed statistically significant differences among male IDUs. All 1b genotype sequences carried the clinically proven drug resistance mutation C316N.

Conclusions The predominant HCV genotype among IDUs in Guangzhou is 6a, with complex sources of genotype introduction. The prevalence of genotypes differs between male and female IDUs, and middle-aged and elderly IDUs are a key population for HCV infection. Additionally, increased attention should be paid to the drug resistance of the 1b genotype.