Serodiagnosis of Helicobacter pylori infection by Cobas Core ELISA in adults from Minas Gerais, Brazil

Abstract

We evaluated the accuracy of a 2nd generation ELISA to detect Helicobacter pylori infection in adults from a developing country in view of variations in sensitivity and specificity reported for different populations. We studied 97 non-consecutive patients who underwent endoscopy for evaluation of dispeptic symptoms. The presence of H. pylori was determined in antral biopsy specimens by culture, by the preformed urease test and in carbolfuchsin-stained smears. Patients were considered to be H. pylori positive if at least two of the three tests presented a positive result or if the culture was positive, and negative if the three tests were negative. Sixty-five adults (31 with peptic ulcer) were H. pylori positive and 32 adults were H. pylori negative. Antibodies were detected by Cobas Core anti-H. pylori EIA in 62 of 65 H. pylori-positive adults and in none of the negative adults. The sensitivity, specificity and positive and negative predictive values of the test were 95.4, 100, 100 and 91.4%, respectively. The Cobas Core anti-H. pylori EIA presented high sensitivity and specificity when employed for a population in Brazil, permitting the use of the test both to confirm the clinical diagnosis and to perform epidemiologic surveys.

Helicobacter pylori infection in adults from a poor urban community in northeastern Brazil: demographic, lifestyle and environmental factors

“…Helicobacter pylori antibodies were assayed with Cobas Core anti-H. pylori IgG EIA (Roche Diagnostic Systems, Basel, Switzerland), a second-generation EIA that employs a well characterized and highly immunogenic purified H. pylori-specific multicomponent antigen preparation containing urease and free of cross-reacting flagellar proteins. The test had previously been standardized for the Brazilian population with 95.4% sensitivity and 100% specificity for adults [12]. This test was used according to manufacturer's instructions.…”

3rd BRAZILIAN CONSENSUS ON Helicobacter pylori

“…All serological tests must be locally validated (137,186) . In Brazil, validation studies have been performed in Campinas and Belo Horizonte (146,169) . Less used in daily practice, research on serum antibodies reactive to CagA protein can be used to detect samples of bacteria carrying the CagA gene.…”

“…Therefore, using additional staining with acidophilic features capable of coloring the organism and not primarily the gastric mucus where it is found is recommended. Among the various existing stains, one of the most recommended because of its simplicity and low cost is Giemsa staining (52,115,169,175) . Histological diagnosis and the urease test may show up to 95% sensitivity depending on the quality of material and expertise of the examiner (137,197) .…”

“…Although serology is unable to define the presence of active infection, in areas where infection is highly prevalent its positivity has a high positive predictive value, and is considered an acceptable diagnostic alternative. The most commonly used serological tests are those performed by ELISA, as previously validated in Brazil (146,169) . To control bacteria eradication in the test-and-treat strategy, only the labeled urea breath test and a fecal antigen survey are recommended, both of which have also been validated in Brazil already (26,189) .…”

IL1RN polymorphic gene and cagA‐positive status independently increase the risk of noncardia gastric carcinoma

“…The presence of IgG antibodies specific to H. pylori was measured by a second-generation ELISA (Cobas-Core anti-H. pylori EIA; Roche, Basel, Switzerland), which had been validated previously for the Brazilian adult population in terms of culture, preformed urease test and stained smear, and which had shown 95.4% sensitivity and 100% specificity. 22 Sera were assayed for anti-CagA antibodies by using a commercial ELISA, Helicobacter pylori p120 CagA (Viva Diagnostika, Hürth, Germany). The antigen employed in the kit is a highly purified protein of 120 kDa, and the assay was performed according to the recommendations of the manufacturer.…”