[Evaluation of methods for the diagnosis of Helicobacter pylori infection]

Helicobacter pylori is a gram negative curved bacillus recognized as etiologic agent of chronic gastritis and an important factor in the development of duodenal ulcer and gastric cancer. The purpose of this work is to evaluate three microbiologic methods for diagnosing H. pylori infection. We studied 375 samples from 218 patients, who consulted at the Department of Gastroenterology of the Hospital Vargas and were candidates for endoscopy. Samples of gastric mucous tissue were taken at level of the antrum and each sample was stained with Gram, tested for urease and cultured.

whit H. pylori positive 123 patients with duodenal ulcer at the endoscopy (91.1%), 17 had gastric ulcer (76.5%), 40 gastritis and/or duodenitis (60.0%), 1 duodenal ulcer and gastric (100.0%) and 37 normal endoscopies (56.8%). Evaluating the three methods used we found that of the 286 H. pylori positive samples, the Gram stain detected 282 (sensibility 98.6% and specificity 96.6%); the urease test 276 (sensibility 96.5% and specificity 98.6%) and culture was positive in 255 samples (sensibility 89.2% and specificity 100.0%). These results show that both the Gram stain and Urease test are useful for diagnosing H. pylori infection due to their high sensitivity and specificity, rapidness, low cost for the Gram stain, and easy interpretation for Urease test. Culture, even though less sensitivity++, represents the most unquestionable diagnosis and permits carrying out susceptibility to antimicrobials tests.