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Comparative performance of contact plates, electrostatic wipes, swabs and a novel sampling device for the detection of Staphylococcus aureus on environmental surfaces

Authors

  • J.K. Lutz,

    1. Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, USA
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  • J. Crawford,

    1. Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, USA
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  • A.E. Hoet,

    1. Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
    2. Division of Epidemiology, College of Public Health, The Ohio State University, Columbus, OH, USA
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  • J.R. Wilkins III,

    1. Division of Epidemiology, College of Public Health, The Ohio State University, Columbus, OH, USA
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  • J. Lee

    Corresponding author
    1. Department of Food Science & Technology, The Ohio State University, Columbus, OH, USA
    • Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, USA
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Correspondence

Jiyoung Lee, 406 Cunz Hall, 1841 Neil Avenue, Columbus, OH 43210, USA. E-mail: lee.3598@osu.edu

Abstract

Aims

To evaluate the performance of four sampling methods [contact plates, electrostatic wipes (wipe), swabs and a novel roller sampler] for recovery of Staphylococcus aureus from a stainless steel surface.

Methods and Results

Stainless steel test plates were inoculated with Staph. aureus, dried for 24 h and sampled using each of the four methods. Samples were either incubated directly (roller, contact plate) or processed using elution and membrane filtration (swab, wipe). Performance was assessed by calculating the apparent sampling efficiency (ASE), analytical sensitivity (Sn) and percentage of replications with positive growth. The wipe demonstrated the best performance across all inoculating concentrations (ASE48 h = 18%; Sn48 h = 7 CFU per 100 cm2). The swab performed well when corrected for area actually sampled (ASE48 h = 24%; Sn48 h = 76 CFU per 100 cm2). Of the contact-based methods, the newly developed roller sampler outperformed the contact plate (roller: ASE48 h = 10%; Sn48 h = 17 CFU per 100 cm2; contact plate: ASE48 h = 0·04%; Sn48 h = 1412 CFU per 100 cm2); both contact samplers performed better at higher inoculating concentrations (6E3 CFU per 100 cm2 for the roller and 6E6 CFU per 100 cm2 for the contact plate). Overall, the electrostatic wipe produced the highest number of replications resulting in positive growth (74%24 h, 91%48 h).

Conclusions

This study demonstrates that selection of the sampling method must be carefully considered, given that different methods have varying performance.

Significance and Impact of the Study

This is the first study assessing static wipes for sampling and one that uses a more real-world-relevant 24-h drying time. The results help with infection control, and environmental health professionals choose better sampling methodologies.

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