Comparative evaluation of vacuum-based surface sampling methods for collection of Bacillus spores

• Published in: Journal of microbiological methods Vol. 95; no. 3; pp. 389 - 396
• Main Authors: Calfee, M. Worth, Rose, Laura J., Morse, Stephen, Mattorano, Dino, Clayton, Matt, Touati, Abderrahmane, Griffin-Gatchalian, Nicole, Slone, Christina, McSweeney, Neal
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2013
• Subjects: analysis of variance; Anthrax; Bacillus anthracis; Bacillus anthracis - isolation & purification; Bacteriological Techniques - methods; Bioterrorism agent; cellulose; Colony Count, Microbial; concrete; Environmental Microbiology; filters; forensic sciences; polytetrafluoroethylene; Specimen Handling - methods; spores; Spores, Bacterial - isolation & purification; stainless steel; Surface sampling; Vacuum; Vacuum sampling; Bacillus anthracis; Surface sampling; Bioterrorism agent; Anthrax; Vacuum sampling
• ISSN: 0167-7012; 1872-8359
• DOI: 10.1016/j.mimet.2013.10.015

In this study, four commonly-used sampling devices (vacuum socks, 37mm 0.8μm mixed cellulose ester (MCE) filter cassettes, 37mm 0.3μm polytetrafluoroethylene (PTFE) filter cassettes, and 3M™ forensic filters) were comparatively evaluated for their ability to recover surface-associated spores. Aerosolized spores (~105CFUcm−2) of a Bacillus anthracis surrogate were allowed to settle onto three material types (concrete, carpet, and upholstery). Ten replicate samples were collected using each vacuum method, from each material type. Stainless steel surfaces, inoculated simultaneously with test materials, were sampled with pre-moistened wipes. Wipe recoveries were utilized to normalize vacuum-based recoveries across trials. Recovery (CFUcm−2) and relative recovery (vacuum recovery/wipe recovery) were determined for each method and material type. Recoveries and relative recoveries ranged from 3.8×103 to 7.4×104CFUcm−2 and 0.035 to 1.242, respectively. ANOVA results indicated that the 37mm MCE method exhibited higher relative recoveries than the other methods when used for sampling concrete or upholstery. While the vacuum sock resulted in the highest relative recoveries on carpet, no statistically significant difference was detected. The results of this study may be used to guide selection of sampling approaches following biological contamination incidents. •Four vacuum-based methods were evaluated for the collection of spores from surfaces.•On concrete and upholstery, the 37mm MCE device had highest recoveries.•For carpet, the 37mm MCE and vacuum sock devices showed highest recoveries.•Laboratory processing times were shortest for the vacuum sock samples.•Sample collection times were greatest for the 37mm cassette devices.