Diagnostic Accuracy of a Noninvasive Test for Detection of Helicobacter pylori and Resistance to Clarithromycin in Stool by the Amplidiag H. pylori+ClariR Real-Time PCR Assay

Abstract

The noninvasive detection of Helicobacter pylori and its resistance to clarithromycin could revolutionize the management of H. pylori-infected patients by tailoring eradication treatment without any need for endoscopy when histology is not necessary. Several real-time PCR tests performed on stools have been proposed, but their performances were either poor or they were tested on too few patients to be properly evaluated. We conducted a prospective, multicenter study including 1,200 adult patients who were addressed for gastroduodenal endoscopy with gastric biopsies and who were naive for eradication treatment in order to evaluate the performance of the Amplidiag H. pylori+ClariR assay recently developed by Mobidiag (Espoo, Finland). The results of the Amplidiag H. pylori+ClariR assay performed on DNA from stools (automatic extraction with the EasyMag system [bioMérieux]) were compared with those of culture/Etest and quadruplex real-time PCRs performed on two gastric biopsy samples (from the antrum and corpus) to detect the H. pylori glmM gene and mutations in the 23S rRNA genes conferring clarithromycin resistance. The sensitivity and specificity of the detection of H. pylori were 96.3% (95% confidence interval [CI], 92 to 98%) and 98.7% (95% CI, 97 to 99%), respectively. The positive and negative predictive values were evaluated to be 92.2% (95% CI, 92 to 98%) and 99.3% (95% CI, 98 to 99%), respectively. In this cohort, 160 patients (14.7%) were found to be infected (positive by culture and/or PCR). The sensitivity and specificity for detecting resistance to clarithromycin were 100% (95% CI, 88 to 100%) and 98.4% (95% CI, 94 to 99%), respectively.

Where to Biopsy to Detect Helicobacter pylori and How Many Biopsies Are Needed to Detect Antibiotic Resistance in a Human Stomach

“…As expected, the bacterial load measured by culture was lower than qPCR quantification (150-times lower) with a positive correlation between these measures [ 40 , 41 , 42 ]. This difference could reflect a loss of bacterial viability between gastrectomy and freezing of biopsies (limited to one hour for the first biopsies to four hours for the last biopsies) and/or due to thawing before seeding on culture plate.…”

Phenotypic and Genotypic Antibiotic Resistance Patterns in Helicobacter pylori Strains From Ethnically Diverse Population in México

“…Sequencing of the H. pylori genome is increasingly more available and less expensive and offers a unique opportunity to identify known and novel mutations in genes associated with resistance to antibiotics. Experimentally confirmed mutations can then be identified using even simpler and cheaper techniques, some commercially available and designed for use with biopsy tissues without the need to isolate H. pylori ( Poel et al, 2019 ; Pichon et al, 2020 ). However, this is only possible after a thorough confirmation of the specific association with resistance in different regions of the world.…”

Listeria monocytogenesfaecal carriage is common and driven by microbiota

“…Lm was considered present when at least 2 of 3 PCR assays were positive. Lm detection threshold was 10 6 CFU/ml of stool.Tested stool samples originated from two cohorts collected and stored on eNat (Copan): (i) the Hepystool cohort that included samples (n=900 samples, 2015-2016) from non-diarrheic patients (inclusion criteria described in69 ) and (ii) stool samples from diarrheic patients, received at the Infectious Agents Department of the University Hospital of Poitiers, France.…”