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Optimization of processing method for recovery of bacteria from wipes used in biological surface sampling



Autumn S. Downey, Sandra M. Da Silva, Jayne B. Morrow, James J. Filliben, Nathanael D. Olson


Environmental sampling for microbiological contaminants is a key component of hygiene monitoring and risk characterization practices utilized across diverse fields of application. However, confidence in surface sampling results, both in the field and in controlled laboratory studies, has been undermined by large variation in sampling performance results. Sources of variation include controlled parameters such as sampling materials and processing methods, which often differ between studies, as well as random and systematic error; however, the relative contributions of these factors remain unclear. The objective of this study was to determine the relative impacts of sample processing methods, including extraction solution and physical dissociation method (vortexing and sonication), on recovery of Gram-positive (Bacillus cereus) and Gram-negative (Burkholderia thailandensis and Escherichia coli) bacteria from directly inoculated wipes. This work showed that target organism had the largest impact on extraction efficiency and recovery precision, as measured by traditional colony counts. The physical dissociation method (PDM) had negligible impact, while the effect of the extraction solution was organism dependent. Overall however, extraction of wipes in PBS with 0.04% Tween 80 (PBST) resulted in highest mean recovery across all three organisms. The results from this study contribute to a better understanding of the factors that influence sampling performance, which is critical to the development of efficient and reliable sampling methodologies relevant to public health and biodefense.
Applied and Environmental Microbiology


Bacillus cereus, Burkholderia thailandensis, E. coli, extraction efficiency, microbiological sampling, surface thermodynamics, wipes


Downey, A. , Da, S. , Morrow, J. , Filliben, J. and Olson, N. (2012), Optimization of processing method for recovery of bacteria from wipes used in biological surface sampling, Applied and Environmental Microbiology, [online], (Accessed June 23, 2024)


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Created August 3, 2012, Updated November 10, 2018