Surface area matters: An evaluation of swabs and surface area for environmental surface sampling of healthcare pathogens

Abstract

Flocked and foam swabs were used to sample five healthcare pathogens from three sizes of steel and plastic coupons; 26 cm², 323 cm², and 645 cm². As surface area increased, 1-2 log₁₀ decrease in recovered organisms (P < .05) was observed. Sampling 26-cm² yielded the optimal median percent of pathogens recovered.

Fig. 1.

Median percent recovered (%R) of 5 organisms (10⁴ CFU/coupon) using foam and flocked swabs from 3 surface areas (26 cm², 323 cm², and 645 cm²) and 2 surface types (steel and plastic) as suspended in artificial test soil (ATS). Note: Box-and-whisker plot: box; interquartile (IQ) range, line: median, whiskers; maximum and minimum data point, closed circle symbols (•): outliers (likely due to clusters of cells being dispersed during spread-plating), open circle symbols (○): median % R values ≤ 9.2%, red box plot to left (26 cm²), green box plot in the middle (323cm²), blue box plot on the right (645 cm²). Swab types: FM, foam swabs; FL, flock swabs; organisms: AB, Acinetobacter baumannii; CD, Clostridioides difficile; KPC, Klebsiella pneumoniae; MRSA, methicillin-resistant Staphylococcus aureus; VRE, vancomycin-resistant Enterococcus faecalis (VRE).