ORIGINAL ARTICLE Evaluation of rayon swab surface sample collection method for Bacillus spores from nonporous surfaces G.S. Brown 1 , R.G. Betty 1 , J.E. Brockmann 1 , D.A. Lucero 1 , C.A. Souza 1 , K.S. Walsh 1 , R.M. Boucher 2 , M.S. Tezak 3 , M.C. Wilson 3 , T. Rudolph 4 , H.D.A. Lindquist 5 and K.F. Martinez 6 1 Sandia National Laboratories, Albuquerque, NM, USA 2 Orion International Technologies, Albuquerque, NM, USA 3 American Staff Augmentation Providers, Albuquerque, NM, USA 4 Tactical Staffing Resources, Albuquerque, NM, USA 5 United States Environmental Protection Agency Homeland Security Research Center, Cincinnati, OH, USA 6 National Institute of Occupational Safety and Health, Cincinnati, OH, USA Introduction Following a biological agent release, such as, the Bacillus anthracis incidents of October 2001, environmental sam- ples are collected and analysed to provide information on initial agent concentration, location and extent of con- tamination, and ultimately confirmation that clean-up goals are achieved (Small et al. 2001). It is critical from a public health perspective that the information obtained is accurate and reproducible. The consequences of an inap- propriate public health response founded on information garnered from an ineffective sample collection method or procedure has the potential for undesired social and eco- nomic impact. Well-developed and validated procedures Keywords sample recovery efficiency, spore sampling, surface sampling. Correspondence G.S. Brown, Sandia National Laboratories, PO Box 5800, MS0734, Albuquerque, NM 87185, USA. E-mail: gbrown@sandia.gov 2006 ⁄ 0667: received 10 May 2006, revised 31 October 2006, and accepted 24 January 2007 doi:10.1111/j.1365-2672.2007.03331.x Abstract Aim: To evaluate US Centers for Disease Control and Prevention recommen- ded swab surface sample collection method for recovery efficiency and limit of detection for powdered Bacillus spores from nonporous surfaces. Methods and Results: Stainless steel and painted wallboard surface coupons were seeded with dry aerosolized Bacillus atrophaeus spores and surface concen- trations determined. The observed mean rayon swab recovery efficiency from stainless steel was 0Æ41 with a standard deviation (SD) of ±0Æ17 and for painted wallboard was 0Æ41 with an SD of ±0Æ23. Evaluation of a sonication extraction method for the rayon swabs produced a mean extraction efficiency of 0Æ76 with an SD of ±0Æ12. Swab recovery quantitative limits of detection were estimated at 25 colony forming units (CFU) per sample area for both stainless steel and painted wallboard. Conclusions: The swab sample collection method may be appropriate for small area sampling (10 –25 cm 2 ) with a high agent concentration, but has limited value for large surface areas with a low agent concentration. The results of this study provide information necessary for the interpretation of swab environ- mental sample collection data, that is, positive swab samples are indicative of high surface concentrations and may imply a potential for exposure, whereas negative swab samples do not assure that organisms are absent from the surfa- ces sampled and may not assure the absence of the potential for exposure. Significance and Impact of the Study: It is critical from a public health per- spective that the information obtained is accurate and reproducible. The conse- quence of an inappropriate public health response founded on information gathered using an ineffective or unreliable sample collection method has the potential for undesired social and economic impact. Journal of Applied Microbiology ISSN 1364-5072 1074 Journal compilation ª 2007 The Society for Applied Microbiology, Journal of Applied Microbiology 103 (2007) 1074–1080 ª 2007 The Authors