Prevalence of Helicobacter pylori resistance to clarithromycin and metronidazole determined by 23S ribosomal RNA and rdxA gene analyses in Hiroshima, Japan

Abstract

These results indicate that the relatively high prevalence of the dual resistance in H. pylori isolates may need special attention and new therapeutic approaches in Japan.

Importance of antimicrobial susceptibility testing for the management of eradication inHelicobacter pyloriinfection

“…The formation of superoxides results in DNA damage[10]. The distinct mechanism of metronidazole resistance in H. pylori has not yet been clearly explained, but some factors that might be relevant to metronidazole resistance mechanisms in H. pylori are transport deficiency, drug modification or export, loss or modification of the biological target, increased activities of DNA repair enzymes, increased expression of TolC homologous genes (namely hp0605, hp0971, hp1327 , and hp1489 ) that upregulate efflux pump activity, reduced activity of nitroreductases, and an enhanced oxygen radical scavenging system[10,29,36,40]. …”

“…However, the predominant metronidazole resistance mechanisms result primarily from mutations in the oxygen-insensitive NADPH nitroreductase gene ( rdxA) and/or the NADPH flavin oxidoreductase gene ( frxA ), which are putative metronidazole nitroreductase-encoding genes related to metronidazole resistance, and secondarily from mutations in the fdxB gene, which encodes a ferrodoxin-like protein[10,40]. High-level metronidazole resistance can be enhanced by inactivation of the reductase encoded by fdxB [41] (ferrodoxin-like protein-encoding gene) and frxA genes[39,41].…”

“…High-level metronidazole resistance can be enhanced by inactivation of the reductase encoded by fdxB [41] (ferrodoxin-like protein-encoding gene) and frxA genes[39,41]. The frxA gene plays a role in converting metronidazole into an active compound that breaks down DNA[40]. Frameshift mutations, missense mutations, deletion of bases, and the presence of an insertion sequence (mini-IS 605 ) have been demonstrated as four mechanisms of rdxA inactivation[37].…”

Antibacterial Resistance Patterns of Helicobacter pylori Clinical Isolates From Gastric Biopsy of Patients in Yazd

“…Helicobacter pylori is a gram-negative bacterium, which plays an important role in the pathogenesis of chronic gastritis, peptic ulcer, duodenum ulcer and gastric carcinoma (1). The bacterium is colonized in the stomach of more than 50% of the world's population (2).…”

Molecular Approaches and Modern Clinical Strategies for the Management of Helicobacter pylori Infection in Japan

“…The prevalence of resistance to metronidazole in H. pylori in Japan has been reported to range between 5% and 12%. 61 The Tokyo H. pylori Study Group examined the rate of eradication in response to the second-line regimen consisting of PPI, amoxicillin, and metronidazole in a multicenter study in the Tokyo metropolitan area. 62 ITT and per-protocol (PP) analyses revealed eradication rates of 87.6% and 90.6%, respectively.…”