Exploring Non-QRDR Mutations in gyrA and gyrB and Their Impact on Quinolone Resistance in Helicobacter pylori

Abstract

This study investigates the role of mutations in the quinolone resistance-determining regions (QRDR) and beyond in the gyrA and gyrB genes of Helicobacter pylori, specifically their contributions to quinolone resistance. While QRDR mutations are well-established as key contributors to resistance, the impact mutations outside the QRDR remains less understood. Using clinical isolates from Korean pediatric patients, the study analyzed both QRDR and non-QRDR mutations through natural transformation and molecular docking to assess their effects on resistance and the ciprofloxacin (CIP) binding structure. Mutations were identified in both gyrA and gyrB, with non-QRDR mutations at positions 134, 190, 705, and 709 in gyrA, and 249 and 624 in gyrB. These non-QRDR mutations were not directly linked to quinolone resistance. However, molecular docking analysis of the 91st position in gyrA revealed significant alterations in the CIP binding structure, which were strongly associated with increased resistance. Moreover, the A134V mutation, although outside the QRDR, was found to accelerate the emergence of spontaneous QRDR mutations, suggesting an indirect role in resistance development. These findings underscore the critical importance of QRDR mutations in H. pylori quinolone resistance, with particular emphasis on the mutation at position 91 of gyrA, which significantly alters the CIP binding structure and correlates with increased resistance. The study provides valuable insights into the mechanisms of antibiotic resistance, enhancing the understanding of H. pylori resistance pathways and informing future research toward developing more effective treatment strategies.