Citation:

Mikelonis, A., A. Abdel-Hady, D. Aslett, K. Ratliff, A. Touati, J. Archer, S. Serre, L. Mickelsen, S. Taft, AND W. Calfee. Comparison of surface sampling methods for an extended duration outdoor biological contamination study. ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, 192(455):13, (2020). https://doi.org/10.1007/s10661-020-08434-8

Impact/Purpose:

If a wide area biological contamination incident occurs due to natural or insidious actions sampling devices are necessary to determine the extent and magnitude of contamination. This journal publication presents the results of a 210 day outdoor field study that evaluated five different sampling methods/devices for their recovery of spores. These data are useful for determining which device is the most effective and efficient at sample collection is a significant step in federal emergency response preparation. The data and discussion included in this paper is of interest to the federal, state, and local emergency responder community.

Description:

Bacillus anthracis, the causative agent for anthrax, is a dangerous pathogen to humans and has a history as a bioterrorism agent. While sampling methods have been developed and evaluated for characterizing and clearing contaminated indoor sites, the performance of these sampling methods is unknown for use in outdoor environments. This paper presents surface sampling data for Bacillus atrophaeus spores, a surrogate for B. anthracis, from a 210-day outdoor study that evaluated the detection and recovery of spores using five different sampling methods: sponge sticks, 37-mm vacuum filter cassettes, residential wet vacuums, robotic floor cleaners, and grab samples of soil, leaves, and grass. Both asphalt and concrete surfaces were sampled by all the surface sampling methods, excluding grab sampling. Stainless-steel coupons placed outdoors were additionally sampled using sponge sticks. Sampling methods differed in their ability to collect detectable spores over the duration of the study. The 37-mm vacuums and sponge sticks consistently detected spores on asphalt through day 37 and robots through day 99. The wet vacuums detected spores on asphalt for days 1 and 4, but not again until day 210. On concrete, all samplers detected spores until day 210 except for sponge stick samplers that detected spores only up until the day 99 time point. For all sampling methods, spore recoveries were higher from concrete than from asphalt surfaces. There was no statistically significant difference in recoveries of sponge sticks and 37- mm vacuums from either asphalt or concrete surfaces. Processing of grab samples was challenging due to non-target background microorganisms resulting in high detection limits for the samples.

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