A comparative study of laboratory methods for detecting Helicobacter pylori antibiotic resistance

The rise of antibiotic resistance in H. pylori has led to a decrease in the effectiveness of eradication therapy. Treatment plans are now chosen based on local antibiotic resistance data, with a primary focus on clarithromycin. An approach tailored to individual patients for H. pylori eradication has been proposed, involving the assessment of antibiotic resistance before starting the initial treatment. The objective of this study is to compare and describe phenotypic and molecular-genetic methods for detecting antibiotic resistance in H. pylori, while also evaluating their diagnostic accuracy. Materials and methods. In this study, we examined 25 cultures of H. pylori with known phenotypic sensitivity and resistance to antibacterial agents. We determined resistance to clarithromycin and levofloxacin through a series of dilutions in Mueller-Hinton agar with added sheep blood, following the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Molecular markers of resistance were analyzed using Sanger sequencing and real-time polymerase chain reaction (RT-PCR) with specific primers. To assess the diagnostic accuracy, we compared the results of these molecular methods with those of the phenotypic method. Results. We established a complete agreement between the results obtained through phenotypic and molecular methods when detecting H. pylori resistance to clarithromycin. When evaluating levofloxacin resistance, we observed that cultures displaying phenotypic resistance also harbored mutations in the gyrA gene associated with resistance. Interestingly, some cultures without phenotypic resistance still exhibited characteristic gyrA gene mutations. The molecular methods demonstrated 100% sensitivity in detecting clarithromycin resistance and 100% sensitivity in detecting levofloxacin resistance, with a specificity of 78.57%. Conclusion. This research highlights a strong correlation between phenotypic and molecular resistance assessments in H. pylori, particularly in the case of clarithromycin. Sanger sequencing and RT-PCR consistently yielded reliable results, underscoring the trustworthiness of these methods.