Review article: nitroimidazole resistance in Helicobacter pylori

Abstract

The efficacy of a nitroimidazole‐containing regimen for the treatment of Helicobacter pylori infection is decreased by nitroimidazole resistance. Nitroimidazoles are meta‐ bolized by H. pylori by several nitro‐reductases of which an oxygen‐insensitive NADPH nitroreductase encoded by the rdxA gene is the most important. Null mutations in this gene are associated with resistance. Susceptibility testing to nitroimidazoles may give variable results. This is not only related to the slow growth under specific conditions, but also to variability in the activity of the other nitroreductases and the ability to deactivate toxic metabolites of an NI and to repair DNA damage. Moreover, co‐infections with resistant and susceptible bacteria are frequently found. The presence of nitroimidazole resistance is related to the previous use of this drug. The prevalence of resistance is rising and nowadays 10–50% of the isolates are resistant. Resistance reduces the efficacy of a treatment regimen to a variable degree. This is related to efficacy of the other components of the regimen and the treatment duration. Whether a nitroimidazole is still effective in resistant strains remains unresolved. When nitroimidazole resistance is present, a nitro‐imidazole‐containing regimen should be avoided or a regimen with other highly effective components should be used.

Increasing Multidrug Resistance in Helicobacter pylori Strains Isolated from Children and Adults in Mexico

“…In Mexico, metronidazole has commonly been used to treat diarrheal diseases for many years (12); this is probably the cause of the high rate of resistance to this antibiotic. We could not demonstrate higher metronidazole resistance in females, despite the fact that gender has been suggested to be a risk factor for resistance to metronidazole, probably because of its use in the treatment of gynecologic infections (14). The value of the E test for testing susceptibility to metronidazole has been questioned recently (11); however, when assay conditions are carefully controlled, results are comparable to those of agar dilution and disk diffusion (8,14).…”

Distinctiveness of Genotypes ofHelicobacter pyloriin Calcutta, India

“…As noted above, MTZ is used frequently against a variety of illnesses in India. The present abundance of Mtz r in Indian H. pylori strains can be ascribed to this frequent use of MTZ, generally at doses that may induce and select for resistant mutants of resident H. pylori strains without eradicating them (59).…”

Appropriateness of Repeating <b><i>Helicobacter pylori</i></b> Culture and Susceptibility Testing Following Failure of Individualized Antibiotic Therapy

“…Nevertheless, robust clinical data would be valuable, since the emergence of resistance is directly linked to the number of prior treatment attempts [16]. CLA resistance develops in those who had previously used CLA, and MET resistance develops in those who had used MET [17,18,19]. In this manner, we are omitting important variables that might directly impact the success of future eradication attempts and might indirectly influence a decision to perform H. pylori culture.…”