Evaluation of swab transport systems against a published standard

Background: Before the publication of the M40-A standard by the United States National Committee for Clinical Laboratory Standards (NCCLS), no quality control data for swab transport systems (STSs) had been available. Aims: To compare three commercially available STSs against the published standard to ascertain bacterial survival after a set holding time. Method: Charcoal and non-charcoal containing swabs were inoculated with standard volumes and numbers of a range of bacteria commonly isolated from clinical material. Bacterial counts were taken at time zero, six, 24, and 48 hours, with the results being compared against the NCCLS standard. Results: The standard clearly differentiated between the three STSs tested, with one product being superior to the other two products in providing better survival. Conclusion: The standard now provides manufacturers and users of STSs with meaningful data to provide, purchase, and compare an STS for routine clinical use.