Effect of Previous Nitroimidazole Treatment on Helicobacter pylori Eradication Success

The goal of this study was to examine the impact of prior treatment with a nitroimidazole antibiotic on the success of Helicobacter pylori treatment.

Prior nitroimidazole exposure may increase the likelihood of nitroimidazole-resistant H. pylori. 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. Data to support this recommendation are lacking.

We searched the Clalit Health Services database to identify subjects 25 to 60 years old who underwent a first-ever C-urea breath test between 2010 and 2015. Patients who underwent a previous H. pylori stool antigen test or gastroscopy were excluded. Pharmacy dispensation data were retrieved.

A total of 1386 subjects (34.8% male individuals, age 40.7±10.7 y) received a nitroimidazole-containing regimen including 282 (20.4%) with prior nitroimidazole exposure. Successful eradication was achieved in 58.9% and 73.8% of subjects with and without prior nitroimidazole exposure, respectively (odds ratio, 0.51; 95% confidence interval, 0.39-0.67; P<0.0001). Nitroimidazole exposure adversely impacted the success of triple therapy with nitroimidazole, proton pump inhibitor, and amoxicillin or clarithromycin (39.4% vs. 63.4% and 54.4% vs. 73.6%, P<0.01, respectively), but not quadruple therapy. Following multivariate analysis, nitroimidazole exposure was significantly associated with eradication failure (odds ratio, 1.89; 95% confidence interval, 1.43-2.50; P<0.0001). A greater time elapsed from nitroimidazole exposure, and a lower cumulative nitroimidazole dose were observed in subjects with successful eradication (P<0.0001 for both).

Nitroimidazole exposure may adversely impact the success of nitroimidazole-based triple therapy, but not quadruple therapy. Clinicians should conduct a thorough patient drug history before administering empiric treatment for H. pylori infection.