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. 2018 Jun 20;18(1):91.
doi: 10.1186/s12876-018-0820-0.

Prevalence of clarithromycin resistance in Helicobacter pylori in Santiago, Chile, estimated by real-time PCR directly from gastric mucosa

Patricio Gonzalez-Hormazabal  1 , Maher Musleh  2   3 , Susana Escandar  2 , Hector Valladares  2   3 , Enrique Lanzarini  2   3 , V Gonzalo Castro  4 , Lilian Jara  4 , Zoltan Berger  2
Affiliations

Prevalence of clarithromycin resistance in Helicobacter pylori in Santiago, Chile, estimated by real-time PCR directly from gastric mucosa

Patricio Gonzalez-Hormazabal et al. BMC Gastroenterol. .

Abstract

Background: Current available treatments for Helicobacter pylori eradication are chosen according to local clarithromycin and metronidazole resistance prevalence. The aim of this study was to estimate, by means of molecular methods, both clarithromycin and metronidazole resistance in gastric mucosa from patients infected with H.pylori.

Methods: A total of 191 DNA samples were analyzed. DNA was purified from gastric mucosa obtained from patients who underwent an upper gastrointestinal endoscopy at an university hospital from Santiago, Chile, between 2011 and 2014. H.pylori was detected by real-time PCR. A 5'exonuclease assay was developed to detect A2142G and A2143G mutations among H.pylori-positive samples. rdxA gene was sequenced in samples harboring A2142G and A2143G mutations in order to detect mutations that potentially confer dual clarithromycin and metronidazole resistance.

Results: Ninety-three (93) out of 191 DNA samples obtained from gastric mucosa were H.pylori-positive (48.7%). Clarithromycin-resistance was detected in 29 samples (31.2% [95%CI 22.0-41.6%]). The sequencing of rdxA gene revealed that two samples harbored truncating mutations in rdxA, one sample had an in-frame deletion, and 11 had amino acid changes that likely cause metronidazole resistance.

Conclusions: We estimated a prevalence of clarithomycin-resistance of 31.8% in Santiago, Chile. Three of them harbor inactivating mutations in rdxA and 11 had missense mutations likely conferring metronidazole resistance. Our results require further confirmation. Nevertheless, they are significant as an initial approximation in re-evaluating the guidelines for H.pylori eradication currently used in Chile.

Keywords: 23S rRNA; Clarithromycin; Helicobacter pylori; Metronidazole; Mutation; rdxA.

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Conflict of interest statement

Ethics approval and consent to participate

This study was approved by the Ethical Committee of the following institutions: University of Chile School of Medicine (#023/2011), and University of Chile Clinical Hospital (#029/2011). The study was performed in accordance with the Declaration of Helsinki. All subjects are adults and gave written informed consent.

Competing interests

The authors declare that they have no competing interests.

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Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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