Rapid detection of Helicobacter pylori in gastric biopsy material by polymerase chain reaction.

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RESUMO

By using primers based on the sequence of a species-specific antigen of Helicobacter pylori (P. O'Toole, S.M. Logan, M. Kostrzynska. T. Wadström, and T.J. Trust, J. Bacteriol. 173:505-513, 1991), a protocol was established for detection of this microorganism in gastric biopsy samples by the polymerase chain reaction (PCR). A single primer pair was used to specifically amplify a 298-bp sequence in a rapid two-step PCR. The primers exhibited the same specificity in PCR as that which we reported for the species-specific gene probe on which they were based. The sensitivity of the method was 20 copies of the target sequence, or 70 bacterial cells, under the lysis conditions used for patient-derived material. When amplification was performed for a saturating number of cycles, visual examination of ethidium bromide-stained gels successfully detected all samples subsequently judged to be positive by Southern hybridization of the gel with a probe specific for the PCR product. The bacterium could be detected in gastric biopsy samples from patients with various gastric diseases, including samples from which the bacterium could not be cultured. Only 9 of 19 patients who tested positive by PCR of gastric biopsy material were positive when a saliva sample was analyzed. Protocols for sample handling which minimized the risk of contamination while maximizing the sensitivity of the reaction were established. The results support a role for PCR in the rapid identification of H. pylori in clinical samples.

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