Helicobacter pylori (H. pylori)infection is one of the most common causes of gastritis and peptic ulcer diseases. Selection of a reliable method for accurate detection of H. pylori infection in dyspeptic patients is of major importance. H. pylori reside the gastric mucous layer of the superficial epithelium, attaches to gastric epithelial cells; mucins are the most important structural component of the mucous gel layer. To date, 12 human epithelial mucin genes have been identified; most of them are expressed in a cell type and tissue specific manner. MUC5AC is the mucin gene product -specific for gastric glands while MUC2 is predominantly expressed in the small and large intestine. Mucin expression could be changed in chronic gastritis and could be a marker of its progression.
Aims: This study has 3 main objectives; first to assess the diagnostic accuracy of H. pylori stool antigen (HpSA) test by enzyme immunoassay (EIA) compared with the standards methods of diagnosis, second to determine the antimicrobial sensitivity of isolated strains and third, to study the effect of H. pylori on gastric MUC5AC and MUC2 protein expression by immunohistochemistry as a prognostic tool of gastritis progression.
Methods: The study included 62 randomly selected patients who underwent upper gastrointestinal endoscopy for evaluation of dyspeptic symptoms. Gastric biopsy samples were taken for culture, histopathology and immune-staining expression for MUC5AC and MUC52. Antimicrobial resistance was determined by disc diffusion method. Stool samples were also collected from all patients for detection of H. pyloriantigen using polyclonal EIA.
Results:the total number of H. pyloripositive cases was 42/62 (67.7%); in 34 of them, H. pylori was detectable by both culture and histopathology, culture was positive in 40/62 and histopathology detect the organisms in 63/62.The HpSA test was positive in 36 from the 42 cases. While it was negative in 16 out of the 20 negative cases as determined by conventional methods. Thus HpSA test had a sensitivity of 85.7%, specificity of 80% and a negative and positive predictive values of 72.7% & 90% respectively. The overall accuracy of the test was 83.8%.
Antimicrobial resistance of H. pyloriisolates to metronidazole, clarithromycin, amoxicillin and tetracycline was 100%, 20%, 57.5% and 5% respectively.
In H. pylori infected patients, the MUC5AC expression and its staining intensity was completely absent in 8/42 (19%), mildly expressed in 12/42 (28.6%), moderately expressed in 22/42 (52.4%). Strong expression was only found in H. pylori negative cases. The staining pattern of MUC 2 was positive in 18 of 42 H. pyloripositive cases (42.9%), all of them displayed mild positive stain.
HpSA EIA is a non-invasive, easy, rapid and reliable method for detection of H. pyloriinfection with a considerable accuracy. Clarithromycin-containing regimens for H. pylori eradication may be preferred to metronidazole-containing regimens in our community. Changes in gastric mucin expression are useful indication for disease progression in H. pylori-associated gastritis and are detectable before histopathological changes.