QUANTITATIVE POLYMERASE CHAIN-REACTION FOR THE DETECTION OF HELICOBACTER-PYLORI IN GASTRIC BIOPSY SPECIMENS

A variety of methods, including the polymerase chain reaction (PCR), a re available for the detection of Helicobacter pylori in clinical samp les, but none of them can adequately quantify the organism, In the pre sent study, the competitive PCR, a rapid and simple method for quantif ication of Helicobacter pylori DNA in gastric biopsies, was used to me asure the amount of DNA present in Helicobacter pylori-positive biopsi es, This method is based on coamplification of an internal standard an d a target DNA sequence with one set of primers, The internal standard was prepared using a nonhomologous fragment of DNA ligated to specifi c primers used to amplify the target DNA, This competitive DNA fragmen t of a desired size and containing primer templates is called a PCR MI MIC, To perform a quantitative PCR, PCR amplification reactions were s piked with known quantities of PCR MIMICs containing unknown amounts o f DNA from Helicobacter pylori-positive biopsies, The amount of target DNA was determined by visual comparison of the PCR products after est ablishment of the correlation between the internal control concentrati on and the DNA concentration in a competitive amplification reaction, The results were confirmed by a radioactive method. Quantitative PCR c an be a reliable method for determining the extent of Helicobacter pyl ori infection.