Purpose: Two alternative methods employing paint rollers or tampons were compared to conventional gauze drag swabs to evaluate their ability to recover Salmonella in agricultural environments.
Methods: Sampling was conducted in a field used to grow cantaloupe and on a small adjacent cattle ranch. Both sites were known to be contaminated with Salmonella. Tampons, paint rollers, and conventional gauze drag swabs were attached to 1 m of cotton string on one end. Individual drag swabs were bagged and sterilized by autoclaving. At the sampling location, each drag swab was aseptically pre-moistened with 400 g of sterile, canned evaporated milk. At each sampling site, 10 swabs of each type (paint roller, tampons, and gauze) were dragged in a U or W pattern. One hundred and four environmental grab, cotton tip, and sponge stick samples were also collected from the farm sites. Drag swabs and the environmental samples were shipped to the laboratory, enriched, and analyzed by culture and molecular typing.
Results: Six of 10 (60%) paint roller samples were positive for Salmonella from the cantaloupe field, and 1 of 10 (10%) conventional drag swabs were positive. From the ranch samples, 4 of 10 (40%) paint rollers, 1 of 10 (10%) tampons, and 4 of 10 (40%) drag swabs tested positive for Salmonella. Multiple different serovars were isolated, though the diversity of serovars isolated from the drag sampling was not as high as that observed in the environmental samples.
Significance: The results of this study indicate the efficacy of using paint rollers as an effective way to sample agricultural environments for the presence of Salmonella.