Image: The H. pylori Ag test is a rapid test for the qualitative detection of Helicobacter pylori antigen in human fecal specimen (Photo courtesy of Standard Diagnostics).
Helicobacter pylori are curved gram negative bacilli and have been etiologically associated with several pathogenic conditions of the stomach ranging from gastritis to gastric cancer. Prevalence of H. pylori infection varies based on several factors globally and in developing countries more than 80% of the population is infected with H. pylori.
Helicobacter pylori antibody titers fall very slowly even after successful treatment. Therefore, tests detecting H. pylori antibody lack specificity and sensitivity. On the other hand, H. pylori stool antigen tests are reported as an alternative assay because of their reliability and simplicity. Serology is a widely available and inexpensive test but with low diagnostic accuracy. On the other hand, the H. pylori stool antigen (HpSA) test has been put in the market as optional technique because of its reliability and simplicity.
Medical scientists at the University of Gondar (Gondar, Ethiopia) conducted a cross sectional study on patients with dyspepsia from February to March 2015 attending the medical outpatient department of the University Hospital. Stool and blood specimens were collected from each patient for serologic tests. The blood was centrifuged until serum was separated and stored at –20 °C. The stool specimens were also stored at –20 °C until the laboratory tests were performed.
A total of 201 dyspeptic patients were included in the study of which 140 (69.7%) were males and 60 (30.3%) were females. The age of the participants ranged from 7 to 85 years with a mean age of 29.5 ±14.85 years. The team evaluated the performance of SD BIOLINE H. pylori Ag rapid test with reference to the commercially available SD BIOLINE H. pylori Ag ELISA and the EZ- STEP ELISA tests. The dBest H. pylori Test Disk was also evaluated.
The team found that 75 (37.1%) of the participants were positive by the SD BIOLINE H. pylori Ag rapid test, while 92 (45.8%) were positive by the SD H. pylori Ag ELISA. The EZ-STEP H. pylori Ag ELISA detected 81 (40.3%) of the samples as positives for H. pylori infection. On the other hand, 68 (33.8%) were positive using both ELISA tests. The dBest H. pylori Test disk detected 143(71.1%) of the samples as positive. The sensitivity, specificity, positive and negative predictive values of the SD BIOLINE H. pylori Ag rapid test were: 95.6%, 92.5%, 86.7%, and 97.6%, respectively.
The authors concluded that The SD BIOLINE H. pylori Ag rapid test has a much better sensitivity, specificity and predictive values compared to the currently available antibody test in the market, in Ethiopia. Therefore, the SD BIOLINE H. pylori Ag rapid stool test could be used to diagnose active H. pylori infection before the commencement of eradication therapy. The study was published on March 5, 2018, in the journal BMC Clinical Pathology.
University of Gondar