Abstract

Objective: The aim of the present study was to determine in vitro susceptibility of isolated Helicobacter pylori strains to fluoroquinolones by disc diffusion method and by genotypic method using polymerase chain reaction and sequencing for determination of gyrA gene mutations at positions 87 and 91 of the H. pylori. Methods: The study included eighty two adult patients complaining of upper gastrointestinal disorders. Biopsy samples were obtained from patients with endoscope and subjected to microbiological culture for H. pylori. Antibiotics susceptibility was determined for the isolates to clarithromycin, amoxicilli n, metronidazole, ciprofloxacin and levofloxacin. Strains of H. pylori resistant to ciprofloxacin were subjected to study by polymerase chain reaction and sequencing for determination of gyrA gene mutations at positions 87 and 91 of the H. pylori. Results: There were high antibiotic resistance tendencies toward clarithromycin (71%) and amoxicillin (47.8%) among isolated H. pylori strains, while resistance patterns were less towards ciprofloxacin (28.9%), levofloxacin (23.2%) and metronidazole (21.7%). GyrA gene mutations were detected in 19 (95%) H. pylori isolates resistant to ciprofloxacin with the most common type mutations in codon A at amino acid position Asp-91 in 12 (63.2%) isolates followed by point mutations at amino acid Asn-87 in 7 (36.8%) isolates. Only one resistant H. pylori strain toward ciprofloxacin had no detected mutations in gyrA gene. Conclusions: The present study highlights the high prevalence of H. pylori resistant strains to amoxicillin and clarithromycin which thought to be the first line of antibiotics therapy. The study draws attention that fluoroquinolone resistance is less than that for first line therapy which may be a better substitute for first line antibiotics. The mechanism of fluoroquinolone resistance is mainly associated with gyrA gene mutations most commonly in the gyrA protein at position 91.