PCR-based diagnosis of Helicobacter pylori infection in Polish children and adults

Infection and associated disease caused by Helicobacter pylori are common in Poland, as in much of Eastern Europe, although the genotypes of strains have not been much studied, especially in terms of traits that might be important in disease. This study developed a sensitive and efficient polymerase chain reaction (PCR) test for the presence of H. pylori in gastric biopsy samples with ureA gene-specific primers and primers for the virulence-associated cag pathogenicity island (PAI). These tests were used with biopsy samples from 246 symptomatic children (age range 1-17 years) and 82 adults (age range 18-53 years) in Warsaw. An assessment was also made of the success of metronidazole-based therapy intended to eradicate infection. H. pylori was detected by ureA-specific PCR in 83 (76.9%) children and in 41 (87.2%) adults with histologically proven gastritis, and in 28.4% and 29.2%, respectively, of the 38 children and 7 adults with little or no evidence of gastritis. In general, H. pylori was detected more often by PCR than by culture (70.3% compared with 52.8% in children and 62.8% compared with 38.6% in adults), although in several cases a negative PCR was associated with a positive culture result. The rate of H. pylori infection increased with age from 5.4% in children up to 5 years old to 29.2% to age 10 and 65.4% to age 18. The tests detected the cagPAI in 97 (75%) and 44 (85%) of the H. pylori-infected children and adults, respectively. Some H. pylori-infected patients with a ureA+ PCR result contained the ‘empty site’ of the cagPAI and only four patients were infected with mixed cag+ cag- strains. PCR with cagPAI and ‘empty site’ of the cagPAI represents a novel tool for fast screening of mixed cag+ cag- infection. These results confirm and further illustrate that direct PCR of biopsy specimens can be useful for detection of infection and genotyping of resident strains, and that H. pylori infection is very common among children as well as adults in Poland. They also show that Polish strains vary with regard to the presence or absence of the cagPAI, and suggest that the proportion of strains that are cag+ is higher in Poland than in Western European countries, which may reflect the relatively higher risk of infection in this society.