Nitroimidazole exposure may dampen efficacy of triple therapy in H. pylori infection

Exposure to nitroimidazole appears to mitigate the efficacy of nitroimidazole-based triple regimen, but not quadruple therapy, in patients with Helicobacter pylori infection, results of a study have shown.

A nitroimidazole-containing regimen was given to 1,386 patients (aged 40.7±10.7 years; 34.8 percent males), including 282 (20.4 percent) with prior nitroimidazole exposure. Of the patients, 58.9 percent and 73.8 percent with and without prior nitroimidazole exposure, respectively, achieved successful eradication (odds ratio [OR], 0.51, 95 percent confidence interval [CI], 0.39–0.67; p<0.0001).

Interestingly, nitroimidazole exposure had an adverse effect on the success of triple therapy containing nitroimidazole, proton pump inhibitor, and amoxicillin or clarithromycin, but not quadruple therapy (39.4 percent vs 63.4 percent and 54.4 percent vs 73.6 percent, respectively; p<0.01).

Multivariable analysis revealed a significant association between nitroimidazole exposure and eradication failure (OR, 1.89, 95 percent CI, 1.43–2.50; p<0.0001). Patients with successful eradication had a greater time elapsed from nitroimidazole exposure and a lower cumulative nitroimidazole dose (p_both<0.0001).

“Clinicians should conduct a thorough patient drug history before administering empiric treatment for H. pylori infection,” the authors said.

The database of Clalit Health Services was accessed to identify individuals aged 25–60 years who underwent a first-ever ¹³C-urea breath test between 2010 and 2015. Those who underwent a previous H. pylori stool antigen test or gastroscopy were excluded from the analysis. Data on pharmacy dispensation were also retrieved.

“Prior nitroimidazole exposure may increase the likelihood of nitroimidazole-resistant H. pylori,“ the authors said. “Current H. pylori treatment guidelines recommend that, in the absence of susceptibility testing, patients with prior nitroimidazole exposure should not be treated with a nitroimidazole antibiotic.”