Evidence from this systematic review suggests that rapid diagnostic assays, especially PCR, for Salmonella, Campylobacter and E. coli O157 are highly accurate. Less is known about the benefits of testing for toxin-producing pathogens and the significance of additional positives detected by these assays. It is unclear whether the additional benefits derived from early diagnosis and more sensitive detection can justify the large set-up costs of rapid tests, particularly if they remain diagnostic adjuncts to culture. Any decisions regarding the use of these assays must consider the speed of diagnosis (including transportation and reporting delays), effect on clinical outcome and costs of implementation simultaneously.
Implications for research The effectiveness and cost-effectiveness of emerging tests for more than one organism at a time, such as multiplex PCR and DNA microarrays technologies, require further investigation. Substantial evidence suggests that rapid assays may be more sensitive than culture methods. Attempting to evaluate diagnostic tests in the absence of a true gold standard creates methodological challenges.
Implications for practice The feasibility of conversion to rapid methods is dependent on localised considerations, including the community prevalence rates for specific pathogens, the skill base and subsequent training costs for laboratory staff and spare capacity available to ensure adequate laboratory space for new equipment. Although these tests show good promise for the future, further studies are needed to assess their immediate use in practice.