Complete Genome Sequences of Helicobacter pylori Clarithromycin-Resistant Strains.

We report the complete genome sequences of two Helicobacter pylori clarithromycin-resistant strains. Clarithromycin (CLR)-resistant strains were obtained under the exposure of H. pylori strain 26695 on agar plates with low clarithromycin concentrations. The genome data provide insights into the genomic changes of H. pylori under selection by clarithromycin in vitro.

GENOME ANNOUNCEMENT

Helicobacter pylori is a spiral Gram-negative bacterium that infects more than half of the world’s population and is currently accepted to play a causative role in the pathogenesis of chronic gastritis, peptic ulcer diseases, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma (1, 2). The eradication of H. pylori not only improves peptic ulcer healing but also prevents its recurrence and reduces the risk of developing gastric cancer (3–6). However, the prevalence of antibiotic resistance in H. pylori is increasing worldwide and is a growing public health problem needing more attention (7–11). Especially, resistance to clarithromycin (CLR) is the most important factor causing treatment failure and is responsible for the decline of the H. pylori eradication rate (7, 12–14).

In the present report, we announce two genome sequences of CLR-resistant H. pylori strains (26695-1CL and 26695-1CH) obtained in vitro. The genomes of these strains provide insights into the genomic changes of H. pylori under CLR selection.

Two CLR-resistant strains were obtained under exposure to low concentrations of CLR in vitro (0.03 and 0.06 µg/ml CLR agar plates), and whole-genome sequencing was performed using 90-base paired-end reads on the Illumina HiSeq 2000 genome sequencer (Illumina, Inc., San Diego, CA). The whole-genome sequences of the two strains were reconstructed by mapping the short-read sequences on the genome of H. pylori 26695 (GenBank accession no. NC_000915) using the CLC Genomics Workbench version 4.0 (CLC bio, Aarhus, Denmark). The lengths of the 26695-1CL and 26695-1CH genomes are 1,667,239 bp and 1,667,302 bp, with coverage depths of 840× and 1,257×, respectively. The G+C content of both strains is 38.87%.

In the two CLR-resistant strains, 5 and 7 mutations (including the well-known mutations in the 23S rRNA gene) were found. Three mutations (C712T, T743A, and G160A in the genes hp0190, hp0471, and hp1048, respectively) were present in both strains. Two mutations were found only in the H. pylori 26695-1CL strain, without mutations in the 23S rRNA gene, and four mutations were found only in the H. pylori 26695-1CH strain, including the A2143G mutation in the 23S rRNA gene.

Nucleotide sequence accession numbers.

The genome sequences of clarithromycin-resistant H. pylori strains 26695-1CL and 26695-1CH were deposited at GenBank under the accession no. AP013356 and AP013355, respectively.