Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates

False-negative rate, limit of detection and recovery efficiency performance of a validated macrofoam-swab sampling method for low surface concentrations ofBacillus anthracisSterne andBacillus atrophaeusspores

“…) and (Piepel et al . ). Prior to each test, spores were diluted to the target spore number using phosphate‐buffered saline (Invitrogen, Waltham, MA) containing 0·02% Tween ® 80 (Sigma‐Aldrich, St. Louis, MO), which we denote as PBS‐T.…”

“…Methods used to measure the surface roughness and porosity of the stainless steel, glass, vinyl tile and plastic ceiling tile materials are described in (Piepel et al . ). The hydrophobicity of the materials was not tested.…”

“…The mean (denoted ), standard deviation (SD) and percent relative standard deviation (%RSD) of the surface concentrations (CFU cm −2 ) from the multiple positive‐control samples for the j th target surface concentration of the i th species were calculated using equations (2)–(4) of Piepel et al . () that account for the structure of the experimental design.…”

“…Appendix C of (Piepel et al . ) contains formulas for calculating surface concentrations recovered, as well as their means and %RSDs.…”

“…An RE was calculated for each test coupon as The mean, SD, %RSD and standard error of REs over multiple coupons were calculated using equations (7)–(10) of Piepel et al . (), which account for the experimental design.…”