Comparision of endoscopy-based and serum-based methods for the diagnosis of Helicobacter pylori

Available commercial tests for the diagnosis of Helicobacter pylori infection are based on different types of antigen preparations and hence the diagnostic utility differs substantially.

To assess the diagnostic value of the determination of Immunoglobulin (Ig) A and IgG antibodies to H pylori whole cell (WC) and IgG antibodies to cytotoxin associated gene A (CagA) using an in-house ELISA in relation to the results obtained with different invasive methods.

The study population consisted of 251 Mexican adults, mean age 53 years, age range 15 to 92 years and female to male ratio of 1.5. Peptic ulcer disease was present in 10.8% of these patients, 5.2% had gastric cancer, 11.2% had esophagitis and 72.9% had nonulcer dyspepsia. Biopsy specimens from the body and the antrum of the stomach were obtained for culture, histology and rapid urease test. ELISAs to detect IgA and IgG WC and CagA antibodies were performed using serum.

H pylori status was established by the results of the invasive tests. Eighty (31.9%) patients positive to the three tests and 38 (15.1%) negative to all the tests were identified. Based on this result, the sensitivity and specificity of the serology assays were 97.5% and 78.9% for the IgG WC and 70% and 73.7% for the IgA WC, respectively. However, if H pylori status was defined by the positive result of at least one or two invasive diagnostic tests, the sensitivity for the IgG WC decreased to 87.3% and 66.7% respectively, but the specificity was essentially the same. Similar results were obtained for the sensitivity and specificity of IgA using the same criteria. A low CagA prevalence was observed (39%).

Testing for serological IgG antibodies to H pylori WC was the best to assess whether infection by H pylori was present. Neither the IgA WC nor the IgG CagA ELISAs add significant value in the diagnosis of H pylori.