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

Abstract

BackgroundCurrent 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.MethodsA 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.ResultsNinety-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.ConclusionsWe 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.

Efficacy of immunohistochemical staining in detecting Helicobacter pylori in Saudi patients with minimal and atypical infection

“…The qRT-PCR analysis of 50 biopsy specimens revealed an H. pylori infection incidence rate of 64%, which was higher than that in other studies, which reported H. pylori infection prevalence of 48.7% and 57% [19,20]. Previous studies in Saudi Arabia have reported that the H. pylori infection prevalence rates ranged from 28-70% with an average of 50% [21].…”

High prevalence of clarithromycin resistance and effect on Helicobacter pylori eradication in a population from Santiago, Chile: cohort study and meta-analysis

“…The specific reasons were: Pediatric population 19 ; Other Latin American population 14,34,35 ; study published before 2010 16,37–39 ; reviews 14,35,38 ; duplicated sample and population from regions outside Santiago 36,37,39,40 . Two studies met the inclusion criteria 17,18 and were analyzed with our study, the combined sample size was 194 patients. PRISMA flow diagram is shown in Fig.…”

Antibiotic Resistance Surveillance of Helicobacter Pylori at the Biobío Region (Chile) in a Decade

“…In addition, increasing of clarithromycin resistance could be expected due to its use in the treatment of extra-digestive infections (19) . Recently, Gonzalez-Hormazabal et al (20) estimated a 31.8% prevalence of clarithromycin resistance in H. pylori at Santiago-Chile by real-time PCR directly from gastric mucosa. These results are higher than the results presented in this work, but it is known that bacteriological cultures underestimate the prevalence of H. pylori as compared to other methods, especially as compared to PCR detection for clarithromycin.…”