C-168. Comparison of Physical Performance Characteristics (Absorption/Release) of Wound Bacteriology Swabs Compared to ESwabs Including Implications for Routine Use of ESwabs

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

Traditionally, commercial swab transport devices almost exclusively utilize a design that winds fiber around a stick with the shape of the bud determined by the winding pattern. ESwabs utilize a swab with nylon fibers that are sprayed (flocked) onto a stick and, unlike traditional swabs that use the swab as the inoculum source, utilize a liquid Amies transport media as the inoculum source. Because flocked swabs appear to offer greater absorption/release than wound swabs, we examined these properties for ESwab flocked swabs (EFS) compared to wound rayon swabs in a series of experiments: (1) To compare absolute absorption, swabs were dipped into organism suspensions. EFS absorbed significantly more liquid than the two other swabs tested while a Starplex rayon swab absorbed significantly more liquid than a Copan rayon swab; (2) To compare release of organisms in a liquid phase, EFS and 4 other wound swabs were vortexed or twirled in saline. Recovery was greatest for EFS, whether the swabs were vortexed or twirled. Recovery was also greater for twirled EFS than for any other swab (vortexed or twirled) with EFS releasing 75-78% of the inoculum by twirling compared to 26-37% by twirling or 43-46% by vortexing for the next best swab; (3) To compare release of organism on a solid phase, we sequentially rolled swabs down the middle of 5 BAPs. Rayon swabs released 2.1-2.7 % of inocula cf. 31% for EFS for GAS and 0.35-0.46% for rayon swabs cf. 53% for EFS for PSA. (4); To compare release with full-plate streaking, we inoculated plates as with a K-B inoculation. Rayon swabs released 18-23% cf. 73% for EFS for GAS and 29% for rayon swabs cf. 85% for EFS for PSA. We also assessed the volume of ESwab inoculum that would produce the same streak pattern as a wound swab and determined that a 30-35 ul inoculum produced a comparable result. Overall, EFS demonstrated superior absorption and release compared to wound swabs. The presence of the inoculum in the liquid phase with ESwab offers the potential for: routine quantitative culture; a more sensitive culture method; performance of different types of cultures from one specimen; and storage of reserved specimen for additional testing as needed.