Stool Microscopy and Culture

These tests all detect a range of potentially harmful organisms within the stool. Microscopy is a test which is not undertaken by all laboratories as a matter of routine unless there is a specific indication to do so. It examines a (fresh- the fresher the better!) stool for a number of pathogens including ova’s cysts and parasites, such as giardia lamblia which can go undetected unless specifically examined for. Even then they can often be difficult to spot. Stool culture uses a number of techniques to try and grow known pathogens from a sample of stool (usually diarrhoea). The commonest pathogen identified in the UK by Gastroenterologists is Campylobacter jejuni. Testing for C. difficle involves an array of tests which vary slightly from centre to centre. These tests include testing to detect an enzyme produced by the bacteria, an assay for the two toxins (A & B) the bacteria can produce, use of PCR to detect the regulatory gene for the two toxins and culture for the bacteria itself as well as genotyping to identify which strain of CDAD is present. Testing usually starts with broad test to detect sign of the bacteria and then narrows as required..