C-167. Evaluation of Seven Microbiology Swab-Collection Devices Including the Use of a Modified M40-A Protocol for Testing ESwabs

P. P. Bourbeau, B. L. Swartz;
Geisinger Med. Ctr., Danville, PA.

The CLSI Standard M40-A includes standards and testing protocols for bacteriological swab transport devices. In this study, we evaluated Copan ESwab and 4 swab transport devices w. rayon swabs: Copan M-40 w. liquid Stuart’s; Copan M-40 w. Amies gel; Starplex STARSWAB II w. liquid Stuart’s; Starplex STARSWAB II w. Amies gel. All 5 swab devices were tested against the four M40-A specified strains of aerobic/fastidious anaerobic bacteria plus the one fastidious organism, N. gonorrhoeae while the 2 Amies gel agar swabs and ESwab were also tested against the 5 strains of anaerobic bacteria specified in M40-A. Testing was performed utilizing 2 storage temperatures: 4C and room temperature (RT) using the M40-A swab elution method. While M40-A describes both a roll-plate and swab elution method for evaluation of swab transport devices, only the swab elution method can accurately be utilized for ESwab. For ESwab, we utilized a modified version of M40-A with the ESwab liquid Amies transport used in place of saline for the primary swab elution. All 5 swabs satisfied the M40-A standard for all organisms tested at both storage temps. Recovery was better at 4C than RT for 28 of 34 swab/org. combinations tested (swab/org. combinations that had overgrowth were excluded). Initial 0 time counts, which reflect organism release from the swab, were significantly higher for ESwab than for each of the other swabs tested for each of the 10 organisms tested. The superior release of organisms from the ESwab combined with the excellent preservation of viability by ESwab offers superior performance in comparison to the other 4 swab transport devices evaluated in this study. We propose that a new factor, which we are calling the recovery index (R.I.) be used to compare swab transport device performance. The R.I. takes into account the release properties of the swab device (flow dynamics) and the preservative qualities of the media. It can be calculated at various times post inoculation, reflecting varying lengths of storage for clinical specimens. R.I. provides more quantitative information than the current pass/fail criteria of M 40A.