Genetic determinants of Helicobacter pylori resistance to fluoroquinolones in phenotypically resistant isolates.

Abstract

Background:Helicobacter pylori is a Gram-negative bacterium that infects the gastric mucosa of approximately 50% of the global population. Although most infections are asymptomatic, H. pylori is a leading cause of peptic ulcers and gastric cancer, which accounts for over 700,000 deaths annually. Fluoroquinolones, such as levofloxacin, are used in second-line therapy for H. pylori eradication. However, increasing resistance to fluoroquinolones, driven by point mutations in the gyrA and gyrB genes, poses a significant public health challenge. Despite this, data on the genetic basis of fluoroquinolone resistance in H. pylori isolates in Uganda remains scarce.Objective:This study aims to identify the genetic determinants of fluoroquinolone resistance in phenotypically resistant H. pylori isolates using Sanga sequencing.Methods: A cross-sectional study was conducted on stored isolates collected from H. pylori symptomatic patients who tested phenotypically resistant to fluoroquinolones. A total of 46 isolates underwent DNA extraction and conventional PCR, yielding 24 samples with amplicons, evidenced by bands on agarose gel electrophoresis. The 24 samples were subjected to sanga sequencing ABI 310, which resulted in 7 good sequences.Results:The 7 sequences that were identified and were aligned with the references genome, did not show any mutations at the codons 87 and 91 of gyrA or any other Quinolone Resistance Determining Region (QRDR).Conclusion: This study demonstrated that while PCR amplification of the gyrA gene in Helicobacterpylori isolates was moderately successful, sequencing efficiency remained low due to challenges related to DNA quality, amplification specificity, and template purity. Keywords: Helicobacter pylori, fluoroquinolone resistance, gyrA mutations, Uganda, Sanga sequencing, antimicrobial resistance.