Detection of Helicobacter pylori in faeces by culture, PCR and enzyme immunoassay

Abstract

Various techniques such as culture, PCR and enzyme immunoassay have been used to detect Helicobacter pylori infection in human faecal specimens. Attempts to culture H. pylori have had limited success as the bacterium exists predominantly in a non-culturable (coccoid) form in the faeces. Several PCR protocols, differing from each other in the choice of genomic targets and primers, have been used to detect H. pylori infection. Substances in faeces that inhibit PCR have been removed by various pre-PCR steps such as filtration through a polypropylene membrane, biochemical separation by column chromatography and isolation of H. pylori with immunomagnetic beads, the former two techniques yielding results with a high degree of sensitivity and specificity. An enzyme immunoassay based on the detection of H. pylori antigen in faeces has become a convenient tool for the pre-treatment diagnosis of the infection. The stool antigen assay is convenient, especially for children, as it involves neither surgery nor the discomfort associated with the urea breath test. However, its applicability in monitoring eradication therapy has been controversial, as the assay can detect dead or partially degraded bacteria long after actual eradication, thus giving false positive results.