High prevalence of Helicobacter pylori clarithromycin resistance mutations among Seattle patients measured by droplet digital PCR.

BackgroundTreatment of Helicobacter pylori infection is often empiric; however, current guidelines for management of Helicobacter pylori infection advise against the use of standard triple therapy (clarithromycin, amoxicillin, and proton-pump inhibitor) when clarithromycin resistance exceeds 20%. We developed and tested a new culture-free assay to detect clarithromycin resistance-conferring mutations to determine the prevalence of H.pylori clarithromycin resistance in patients from the United States Pacific Northwest. Materials and MethodsDroplet digital PCR (ddPCR) was used to detect the H.pylori 23S rRNA gene, and resistance-conferring mutations, in archived, formalin-fixed, paraffin-embedded (FFPE) gastric tissue and to retrospectively determine the prevalence of clarithromycin-resistant H.pylori among 110 patients at an academic medical center in the Northwest United States between 2012 and 2014. ResultsOf 102 patients with the H.pylori 23S rRNA gene detected by the ddPCR assay, 45 (44%) had clarithromycin resistance mutations. Thirty-three of the 45 patients with clarithromycin resistance mutations had a mix of wild-type and resistance alleles. Prevalence of clarithromycin resistance mutations differed among racial groups and was highest among Asians, with mutations detected in 14 (67%) of the 21 patient samples. ConclusionsThe prevalence of clarithromycin resistance detected in this region exceeds 20%, indicating that standard triple therapy should not be the first-line antibiotic treatment for H.pylori infection. Culture-free assays for detecting clarithromycin resistance mutations can be performed on archived tissue samples and will aid in informing tailored treatment for effective H.pylori eradication.