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

Various techniques such as culture, PCR and enzyme immunoassay have been us ed to detect Helicobacter pylori infection in human faecal specimens. Attem pts to culture H. pylori have had limited success as the bacterium exists p redominantly in a nonculturable (coccoid) form in the faeces. Several PCR p rotocols, differing from each other in the choice of genomic targets and pr imers, have been used to detect H. pylori infection. Substances in faeces t hat inhibit PCR have been removed by various pre-PCR steps such as filtrati on through a polypropylene membrane, biochemical separation by column chrom atography and isolation of H. pylori with immunomagnetic beads, the former two techniques yielding results with a high degree of sensitivity and speci ficity 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.