An evaluation of faecal transport swabs using the swab elution method in accordance with approved standard CLSI M40-A2

Elcocks, Ellena; Spencer-Phillips, Peter; Adukwu, Emmanuel

Abstract

Introduction
Efficient absorption, transportation and release of specimens from faecal transport swabs are characteristics that commercial swabs must possess to be compliant with the M40-A2 criteria. The aim of this study was to evaluate and compare the recovery efficacy of three faecal transport swabs using the quantitative elution method of CLSI M40-A2 adapted for enteric bacteria.

Method
In this study, the swab elution method outlined by CLSI M40-A2 was employed. Escherichia coli, Shigella flexneri and Salmonella typhimurium are specified in M40-A2 for the validation of faecal transport devices. Three commercially available devices were compared: MWE Fecal Transwab® (foam tip) , MWE Fecal Transwab PF (flock tip) and Copan FecalSwab™ (flock tip). Test organisms were prepared in phosphate buffered saline with a final concentration of approx. 2.0 x 107 CFU/ml. 50µl of culture was used to inoculate the swabs and inoculated devices were held at controlled room temperature (RT) and 4°C. Viable counts were determined at 0, 24, 48 and 72 h.

Results
The number of viable organisms remained stable when stored at 4°C and there was less than 1 log increase or decrease over the 72 hour period for the test organisms and the three swab types.

At RT, the MWE Fecal Transwab® also maintained viable counts of all three organisms with less than 1 log change in CFU/ml. For the MWE Fecal Transwab PF, at RT, there was a >2 log increase in CFU/ml increase for E. coli, approximately 2 log reduction for S. Typhimurium, whilst no change in log CFU/ml was observed for S. flexneri. At the same storage condition i.e. RT, there was an increase in viable count for all three organisms with the Copan FecalSwab™ with 3.02 log CFU/ml increase in viability for E. coli, and an increase of 2.51 log and 2.61 log respectively for S. flexneri and S.typhimurium.

Conclusion
At 4°C the recovery of microorganisms was maintained for 72 h for all three swabs, compared to swabs stored at RT and thus the three swabs were compliant with the M40-A2 protocol at the cold temperatures. M40-A2 compliance was also observed with both MWE Fecal Transwab® (for all organisms) and MWE Fecal Transwab PF at RT with less than 3 Log decline in CFU between Time 0 and 72 hours. The Copan FecalSwab™ at RT was M40-A2 compliant for S. flexneri and S.typhimurium but borderline for the tested E.coli strain.

• Presentation Conference Type: Poster
• Conference Name: Scientific Spring Meeting KNVM & NVMM 2017
• Start Date: Apr 11, 2017
• End Date: Apr 11, 2017
• Deposit Date: Jan 7, 2023
• Publicly Available Date: Jan 11, 2023
• Public URL: https://uwe-repository.worktribe.com/output/10307752
• Related Public URLs: https://www.scientificspringmeeting.nl/; ; https://na.eventscloud.com/ereg/inactive.php?eventid=210895