Investigation of presence of helicobacter pylori in fecal samples, by various primers and DNA isolation methods using polymerase chain reaction method and comparison of results with immunochromatographic detection method

Helicobacter pylori is a carcinogenic bacterium which causes chronic gastric, gastroduodenal ulcers, gastric adenocarcinoma and lymphoma in human being. There is no gold standard test available for diagnosis of H. pylori therefore tests that require endoscopy for diagnosis and monitoring of treatment success are still being used as a reference.This study analyzed the presence of H. pylori in stool samples sent by Department of Medical Microbiology Laboratories by an immunochromatography method, using various DNA isolation protocols and primers, conventional PCR and real time PCR, finally the results were compared.Stool DNA isolation kit (Epicentre), phenol-chloroform extraction method and ethanol precipitation method were used to isolate DNA from stool samples.DNA was isolated successfully by phenol?chloroform extraction and ethanol precipitation methods while fecal DNA isolation kit failed.Among conventional PCR protocols with specific primers targeted to vacA, ureA, ureC gene regions of H. pylori, only 411 bp yield was obtained with HPU1-HPU2 primers on ureA gene successfully in samples.From 54 samples involved in this study, 43 by HpSA, 42 by ureA PCR and 34 by real time PCR were determined as H. pylori positive.If we accept the microbiological examination results of gastric biopsy specimen as a standard, then sensitivity and specificity of the methods used are as below: HpSA test 100%, 46%, ure A PCR 92.86%, 53.85% and 92.86%, 46.15% for real time PCR, respectively.Results agreement between HpSA and ureA PCR was 76% while this was 80% between HpSA and real time PCR.As a result assessing H. pylori?s DNA by a noninvasive method in stool samples has as diagnostic value as an antigen test. However, because of the advantages of using the HpSA test, it was suggested to be more logical.