Differences in outcome according to Clostridium difficile testing method: a prospective multicentre diagnostic validation study of C difficile infection.

Background: Diagnosis of Clostridium difficile infection is controversial because of many laboratory methods, compounded by two reference methods. Cytotoxigenic culture detects toxigenic C difficile and gives a positive result more frequently (eg, because of colonisation, which means that individuals can have the bacterium but no free toxin) than does the cytotoxin assay, which detects preformed toxin in faeces. We aimed to validate the reference methods according to clinical outcomes and to derive an optimum laboratory diagnostic algorithm for C difficile infection.

Selective testing of ß-galactosidase activity in the laboratory identification of Salmonella and Shigella species.

Background: Salmonella and Shigella species are pathogens of great medical and public health importance. However, laboratory identification of these organisms is time consuming. Using current standard laboratory algorithms, the vast majority of organisms submitted for serological typing with Salmonella-specific and Shigella-specific antisera are not clinically significant.