Supplementary Material for: Gastric Wash-Based Molecular Testing for Antibiotic Resistance in <i>Helicobacter pylori</i>

<i>Background:</i> A number of noninvasive tests have been developed to establish the presence of <i>Helicobacter pylori</i> infection. However, thus far these tests have only been capable of detecting its presence. An increasing number of antibiotic-resistant <i>H. pylori</i> infections have been reported and they are known to be correlated with 23S rRNA single nucleotide polymorphisms (SNPs). We hypothesized that genomic analysis of <i>H. pylori</i> recovered from gastric washes could not only be less invasive, but also useful as a screening test and for assessing the outcome of eradication therapy. <i>Methods:</i> Biopsy specimens and gastric washes were collected from 100 patients during endoscopic examination. Then we analyzed 23S rRNA, <i>ureA</i>, and <i>cagA</i> genes using PCR and high-throughput pyrosequencing analysis. <i>Results:</i> Forty-five percent (44/97) of patients tested positive for <i>ureA</i> and 42.3% (41/97) tested positive by a rapid urease test. One hundred percent (35/35) of patients who tested positive by both methods were observed to have the <i>cagA</i> gene. Among these 35 patients, 23S rRNA SNPs were present in 34.3% (12/35). <i>Conclusions:</i> Gastric wash-based PCR and a pyrosequencing assay were used to rapidly detect and estimate the number of 23S rRNA SNPs in clinical isolates of <i>H. pylori</i>. Not only is this a less invasive technique, but it can also diagnose drug resistance.