Objective: Today in the treatment of chronic hepatitis B (CHB) treatment, interferon/pegylated interferon and several nucleoside/nucletide analogues are used. Nucleoside analogues used in the treatment are lamivudine, entecavir and telbivudine whereas tenofovir and adefovir are the nucleotide analogues in use. However, mutations in various regions of viral polymerase gene due to use of nuceloside/ nucleotide reduce the effectiveness of the drug. analogues by inducing antiviral resistance. In this study investigation of the mutations responsible for drug resistance in patients with CHB infection was aimed.

Material and Methods: Forty-five patients who were being followed with the diagnosis of CHB in polyclinics and clinics of Erciyes University Medical Faculty were included in the study. Mutations responsible for drug resistance in reverse transcriptase gene region were investigated by pyrosequencing method (Pyromark, Qiagen, Germany).

Results: Mutations related to drug resistance were detected in 13 of 45 patients. M204I and L180M+M204I, mutations were detected in four samples each, L180M+M204V+V173L and L180M+ M204V mutations in two and three samples respectively. These mutations were reported as follows: M204I; resistant to telbivudine and lamivudine, intermediately susceptible to entecavir and adefovir, and susceptible to tenofovir, L180M+M204I; resistant to lamivudine, telbivudine and entecavir, susceptible to adefovir, tenofovir, L180M+M204V+V173L; resistant to lamivudine, telbivudine and entecavir, susceptible to adefovir, tenofovir, L180M+M204V; resistant to telbivudine and lamivudine, intermediately susceptible to entecavir and adefovir, and susceptible to tenofovir. Treatment of patients was carried out according to the antiviral drug resistance results.

Conclusion: It has been conjcluded that analysis of antiviral drug resistance should be performed in patients with CHB.