Genotyping and antimicrobial resistance patterns of Helicobacter pylori in human and dogs associated with A2142G and A2143G point mutations in clarithromycin resistance

Background: Routes of transmission of Helicobacter pylori a class I carcinogen bacterium and the roles of animals have not been yet well determined. This study was carried out to investigate H. pylori phenotypically and genotypically in human and dogs to determine the antibiotic resistance patterns. As eradication therapy depends mainly on clarithromycin we evaluated 23S rRNA gene mutations associated with its resistance. Results: A total of 150 human stool samples and 60 canine gastric biopsies were examined by nested PCR for the presence of H. pylori, 60% and 76.6% were positive respectively. Only 20 (22.2%) and 41 (89.1%) isolates were successfully cultured from human and canine samples respectively. Genotyping revealed a total of cagA(+) vacA(+) combinations 76.6% (69/90) and 65.2% (30/46) in human and dogs, respectively. Allelic diversity in vacA gene was obviously observed, while cagA(-)vacA(+) combinations were 23.3% (21/90) and 34.7% (16/46) in human and dogs, respectively. The antimicrobial susceptibility patterns of human exhibited the highest levels of resistance against Clarithromycin (60%), Trimethoprim (55%), metronidazole (45%), amoxicillin (45%) and cefsulodin (60%) antibiotics and comparatively lower for spiramycin (10%) and tetracycline (15%). Dogs strains showed the highest levels of resistance against Clarithromycin (53.6%), metronidazole (51.2%) and erythromycin (43.9%) antibiotics, on the other hand, the percent of resistant canine strains were comparatively lower for spiramycin (9.7%). Single point mutation of A2143G was detected as 25% (3/12), 18.1% (4/22) in human and dogs respectively. Single point mutation of A2142G was detected as 16.6% (2/12), 13.6% (3/22) in human and dogs, respectively. While dual mutations of both A2142G and A2143G were detected as 50% (6/12), 40.9% (9/ 22) in human and dogs, respectively. Conclusion: occurrence of elevated rates of A2142G and A2143G point mutations in clarithromycin resistant H. pylori isolates from human and dogs causing failure in treatment and eradication of the pathogen. The roles of animals need attention and further investigations.