Polymerase chain reaction versus culture in the diagnosis of Helicobacter pylori infection

In the management of Helicobacter pyloriinduced gastroduodenal disease, a pilot study at our hospital (St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway) revealed that culture often seemed to fail compared to the polymerase chain reaction (PCR). A more thorough evaluation was therefore undertaken. We included 201 patients referred to upper gastrointestinal endoscopy in the period 2002-2004. Serology, biopsy rapid urease test, culture and PCR were performed. Conventional PCR was performed using the ureC, vacA and cagA genes, and real-time PCR for ureC. A diagnostic standard was defined on the basis of all four tests, and all four tests were then compared to this standard. One hundred eleven patients were deemed H. pylori-positive by the defined diagnostic standard, and 90 were labeled negative. Compared to this standard, culture showed a sensitivity of 87.4%, which was significantly lower than PCR at 99.1% (P<0.001). Culture showed a perfect specificity of 100%, which was significantly better than PCR at 97.8%. ureC was the gene with the best sensitivity (94.6% in conventional PCR, 97.3% in real-time PCR). vacA sensitivity was 87.4%, which is significantly lower than ureC (P<0.001). cagA was present in 37.8% of our H. pylori-positive patients. By real-time PCR a significantly lower cycle threshold was observed in antral biopsies than in corpal biopsies, indicating a higher H. pylori DNA template concentration in antral biopsies. PCR-testing for H. pylori is faster and significantly more sensitive than culture. Culture on the other hand was significantly more specific than PCR in our hand.