COMPARISON OF A NOVEL MULTIPLEX PCR ASSAY AND CLOtest TEST FOR THE DIAGNOSIS OF H. PYLORI

Abstract

Purpose: Several methods may be used clinically to diagnose H. pylori infection, including endoscopy with biopsy, rapidurease test, urea breath test, serologic antibody test, and stool antigen assay. If the test results indicate H. pylori infection, appropriate medication can successfully eradicate H. pylori in most individuals. The CLOtest rapid urease test is widely used in clinical practice to detect the urease enzyme of H. pylori in gastric mucosal biopsies and many physicians even considered it as a gold standard method. However, all the common clinical tests are not sensitive and specific enough to accurately diagnose H. pylori infection. Although PCR is a rapid, sensitive method for the detection of H. pylori from gastric biopsy specimens, the potential problems of many conventional PCR methods are false positive or negative results. To overcome those problems, a novel one-step multiplex PCR detection system was developed. This system can amplify 10 DNA fragments from 5 DNA regions (0.86kb DNA fragment, 706bp and 574bp; Urea A gene, 526bp and 465bp; 16S RNA, 371bp and 315bp; 26kDa, 277bp and 183bp; HpaAgene, 138bpand 118bp) in the genome of H. pylori at the same time. The objective of this study was to assess the diagnostic value of this new multiplex PCR assay to detect H. pylori infection, by comparison with the common clinically used CLOtest methodTable: Sensitivity and specifity of CLOtest relative to Multiplex PCR methodMethods: This study was performed in 76 patients with dyspepsia symptoms undergoing endoscopy in Evanston Northwestern Healthcare. To overcome the problem of patchy H. pylori, the same gastric specimen was used for both CLOtest and PCR assay. The CLOtest test was performed first, once the result (waiting from 20 minutes to 24 hours) was read, the specimen in the CLOtest gel was collected, and then DNA isolation and the one-step multiplex PCR were performed. Results: Positive results were achieved in 64/% (49/76) with multiplex PCR and 43/% (33/76) with CLOtest respectively. The sensitivity and specificity of CLOtest relative to Multiplex PCR is 65% (32/49) and 96% (26/27) respectively. Conclusions: Our results suggest that our multiplex PCR method is a highly specific and sensitive method in the detection of H. pylori when an invasive diagnostic is justified.