A Novel Stool PCR Test for Helicobacter pylori May Predict Clarithromycin Resistance and Eradication of Infection at a High Rate

Abstract

Clarithromycin-based regimens are commonly used as a first-line therapy for Helicobacter pylori-positive patients; however, resistance to clarithromycin has led to treatment failures. The aim of this study was to evaluate the feasibility of using stool samples to detect the presence of H. pylori DNA while concurrently detecting mutations associated with resistance to clarithromycin. For this purpose, total DNA was extracted from 294 raw stool specimens from H. pylori-positive and -negative patients. TaqMan real-time PCR amplification was used to detect the presence of H. pylori as well as to predict the phenotype of the organism and the related outcome for patients treated with clarithromycin. Clarithromycin resistance was determined upon analysis of the PCR result. Patients were also tested by a urea breath test and were subjected to esophagogastroduodenoscopy, followed by histology, culture, and a rapid urease test, in order to obtain a consensus patient infection status. Of 294 total stool samples, 227 were deemed true positive. The sensitivity of H. pylori detection by PCR was 93.8%. Of 213 true-positive samples that were sequenced, 36.2% showed point mutations associated with clarithromycin resistance (A2142C, A2142G, A2143G). The final correlation of the mutant genotypes as determined by sequencing with the eradication of infection was 86%. We found that Helicobacter pylori DNA can be detected in human stool specimens with high sensitivity and can therefore be used to determine the presence of the bacterium without obtaining a biopsy sample. Moreover, genotypic resistance to clarithromycin can be predicted without obtaining a biopsy sample, facilitating the choice of the right therapeutic approach.

Systematic review: Would susceptibility‐guided treatment achieve acceptable cure rates for second‐line Helicobacter pylori therapy as currently practiced?

“…Main limitation is the presence of PCR inhibitors of the stool that may cause false-negative results. 53 In addition, the second part of the study shows that SGT alone would not have achieved optimal cure rates for rescue treatment in a significant proportion of the studies. According to our data, SGT would obtain cure rates above 90% in 21 (56.7%) arms, including 708 patients of 1190 with susceptible strains.…”

“…Although new susceptibility analysis using PCR in stool has been developed, evidence on their efficacy is inconsistent. Main limitation is the presence of PCR inhibitors of the stool that may cause false‐negative results …”

Diagnosis of Helicobacter pylori infection

“…Thus, this study has shown that H. pylori can be detected in human stool samples with high sensitivity and can therefore be used to determine the presence of the bacterium without obtaining a gastric biopsy. Moreover, this technique can also detect clarithromycin resistance …”

“…Moreover, this technique can also detect clarithromycin resistance. 13 Bicak et al investigated the dental biofilm and the saliva of children to detect H. pylori. Seventy dyspeptic children and 30 nondyspeptic children were enrolled in this study.…”

“…In addition, Suki et al 21 demonstrated a positive association between H. pylori infection and increased BMI (especially in patient groups with obesity). Furthermore, high BMI and stroke were associated with unsuccessful eradication, using 13 C-UBT at 6-8 weeks after initiation of therapy. 22…”