DETECTION OF HELICOBACTER PYLORI ANTIGEN IN STOOL BY ENZYME-LINKED IMMUNOSORBENT ASSAY AND COMPARISON WITH CONVENTIONAL METHODS

Helicobacter pylori (H. pylori) bacteria are 'slow' bacterial pathogens and are associated with gastritis, peptic ulcers, gastric adenocarcinoma and gastric Mucosa-Associated Lymphoid Type (MALT) B-cell lymphomas. Several methods, both invasive and non-invasive, are available for detection of H. pylori infection. Invasive methods involve endoscopy and examination of gastric biopsies, e.g. by culture, rapid urease test or histology and are not appropriate for large-scale population studies. Non-invasive methods include the urea breath test, serology and stool antigen test. The latter approach is non-invasive, does not require highly specialized equipment and unlike serology is more likely to provide evidence of active rather than past infection. Furthermore, it may be more appropriate for use in paediatric patients, where techniques such as serology are insensitive and invasive methods are undesirable. Additionally, it may be used for treatment follow-up purposes. Pathogen-specific stool antigen tests are a valid alternative to the Urea Breath Test for non-invasive detection of H. pylori. METHODOLOGY A total of 120 patients who underwent upper gastrointestinal endoscopy for various gastrointestinal disturbances like dyspepsia were included in the study. Stool samples were obtained from the patient on the day of endoscopy and stored at - 20 degrees C. Three biopsy samples were collected, two from the gastric antrum and one from the corpus. One biopsy sample from the antrum was used for performing Rapid urease test at the Endoscopy room and the other two samples were placed in 10% formalin and sent to the laboratory for histopathological examination. RESULTS Sensitivity, specificity, positive and negative predictive values of ELISA was 100%, 77%, 52% and 100% respectively. CONCLUSION H. pylori stool antigen (HpSA) is suitable to use particularly in developing countries and for selection of patients for endoscopy. Detection of HpSA shows high sensitivity and specificity and might be useful for non-invasive diagnosis of H. pylori infection in children and adult patients.