Genotypic and Phenotypic Resistance to Clarithromycin in Helicobacter pylori Strains

Abstract

Background: The increasing prevalence of antimicrobial resistance, together with the lack of novel treatment options, negatively affects successful eradication of Helicobacter pylori. The aim of this study was to investigate genetic mutations in the 23S rRNA genes, which is associated with clarithromycin resistance, and to determine the clinical impact of genotype on phenotypic antimicrobial resistance. Methods: A total of 46 H. pylori strains were obtained from 13 patients, before and after unsuccessful eradication with clarithromycin-based triple therapy. The phenotypic resistance of each H. pylori strain was determined by minimum inhibitory concentration against clarithromycin using the serial two-fold agar dilution method. The genomic sequences of 23S rRNA genes were identified through next-generation sequencing, and nucleotide variants were determined based on comparison with genome sequences of the reference strain H. pylori 26695. Results: Clarithromycin resistance was found in 9 of 13 subjects before treatment and all subjects after unsuccessful eradication. Whole-genome sequencing of the 23S rRNA genes detected 42 mutations on 40 nonidentical loci, including 2147A>G (formerly 2143A>G) and 2146A>G (formerly 2142A>G). All strains with clarithromycin-resistant phenotype had either 2147A>G or 2146A>G mutation. When comparing genotype and phenotype for clarithromycin resistance, there was a significant association between 2147A>G mutation and clarithromycin-resistant phenotype. Conclusions: All clarithromycin-resistant strains had either 2146A>G or 2147A>G mutation, suggesting that tests targeting these two mutations may be enough for the prediction of clarithromycin resistance in this population.

Next Generation Sequencing for the Prediction of the Antibiotic Resistance in Helicobacter pylori: A Literature Review

“…Investigating clarithromycin resistance with traditional molecular methods, a high number of mutations have been detected in the macrolide-binding site of 23SrRNA gene, i.e., A2142G, A2142C, A2143G, T1942C, G1939A, C2147G, G2172T, T2182C, A2116G, A2144G/T, A2115G, G2111A, T2717C, T2289C, G2224A, and C2245T (in accordance to Taylor et al numbering) [ 4 , 5 , 6 ]. In general, NGS has confirmed that clarithromycin resistance is mainly based on point mutations in nucleotide positions 2142 (A to G/C) and 2143 (A to G) in the 23SrRNA gene [ 7 , 8 , 9 ]. The commercially available qPCR (quantitative Polymerase Chain Reaction) assays for the detection of A2142C/G and A2143G, would be sufficient to monitor CLA resistance in clinical practice; but only a limited number of nucleotide position can be analysed with this tool, while whole genome sequencing (WGS) delivers a more comprehensive description of resistance determinants present in a clinical isolate and may detect new mutations potentially conferring drug resistance.…”

A Survey of Helicobacter pylori Antibiotic-Resistant Genotypes and Strain Lineages by Whole-Genome Sequencing in China

“…The point mutations A2143G and A2142G/C in the 23S rRNA gene have been reported to be associated with clarithromycin-resistant strains of H. pylori isolated from Western countries ( 52 – 54 ). Gong et al ( 55 ) noted that all patients developed clarithromycin resistance after failure of clarithromycin-based triple therapy for eradication, whereas 23S rRNA sequencing revealed they all had A2143G or A2142G mutations. Our results showed that the samples with the A2143G mutation in 23S rRNA were all clarithromycin-resistant strains.…”

Effect and Safety of Helicobacter pylori Eradication Treatment Based on Molecular Pathologic Antibiotic Resistance in Chinese Elderly People

“… 1 , 8 The increasing prevalence of antibiotic resistance is our main concern in treatment of H. pylori infection, which can lead to significant eradication failure. 9 , 10 In China, the resistance rates to clarithromycin, metronidazole, and levofloxacin, are already high. One study from Nanjing showed that the H. pylori resistance rates to clarithromycin, levofloxacin and metronidazole were 47.03%, 33.59% and 80.76%, respectively.…”