Evaluation of Non Invasive versus Invasive Methods for Diagnosis of Helicobacter pylori Infection among Patients with Gastroduodenal Disorders.

H. pylori, a spiral gram-negative bacterium, is associated with gastroduodenal diseases. All H. pylori diagnostic assays have limitations. Cytotoxin-associated gene A (cag A), a virulence marker, can be identified by PCR. We evaluated H. pylori diagnostic methods, invasive: rapid urease test (RUT), and histopathological examination (HE), and serology as non-invasive method. Positive cases were studied for presence of cag A gene. Upper endoscopies and gastric biopsies were performed on 67 dyspeptic patients for RUT, HE and PCR. Anti H. pyloriIgG were measured by ELISA. Of 67 dyspeptic patients, 23 (34%) had more than one endoscopic finding, 46 (68.7%) were H.pylori positive by HE, and 21(31.3%) were negative with variable grades of mucosal antral neutrophil infiltration. Of the 46 HE positives, PCR detected CagA in 22 (47.8%). Using HE as the gold standard test, the sensitivity of ELISA and RUT was 93.48% and 86.96%, respectively; and the specificity was 85.71% and 47.62%, respectively. In conclusion, IgG detection by ELISA is a suitable screening test for diagnosis of H. pylori associated gastroduodenal diseases. Histopathology should be performed in ELISA negative cases to exclude infection.