Assessment of selected tests in diagnostics of Helicobacter pylori infections

UNLABELLED: In the diagnostics of Helicobacter pylori infections the invasive and noninvasive methods are applied. In the epidemiological studies the measurement of antibodies of IgG class against H. pylori in the serum or the respiratory test is used. The aim of the study was comparative evaluation of diagnosing of H. pylori infection on the basis of the measurement of antibodies in the serum, HpFL antigens in stool and culture of biopsy specimens from the gastric mucous. MATERIAL AND METHODS: The study included 380 children aged 1-18 years drawn randomly for epidemiological analysis of H. pylori infection in Lower Silesia in the year 2001. The study was conducted in the year 2002. In all children the concentration of antibodies against H. pylon' of IgG class in the serum using the ELISA method as well as H. pylori antigen (HpFL) in stool were determined. In 66 children out of the whole group the measurements of antibodies using ELISA method and immunoblotting as well as HpFL test were compared to the results of H. pylori culture. Additionally the Hp Cag (+) strains were determined. RESULTS: The study demonstrated that in 10% of patients with negative results of IgG class antibodies against H. pylori measurement in the serum (below 24 U/ml) the HpFL test in stool was positive. The sensitivity of the test was 58.9%, specificity 90.0%. The correspondence of HpFL test with positive test for the antibodies in the serum was 90% for the antibodies concentration above 500 U/ml. Assuming that a definite test for the H. pylori infection is culture, the most accurate test for detection of the infection turned out to be the determination of the antigen in the stool and immunoblotting. The parallel increase of antibodies titre together with the increase of prevalence of infection with Hp Cag (+) strains was demonstrated. CONCLUSIONS: The results of HpFL test in stool samples are comparable to the culture, immunoblotting and antibodies concentration in the serum above 100 U/ml.