Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: Jan 30, 2025

Assessing the Biosecurity Risk of Footwear as a Fomite for Transmission of Adventitious Infectious Agents to Mice

DVM, MS,
DVM,
DVM, DACVP,
MPH,
DVM, PhD, MS, DACVP,
BS,
PhD, MS,
VMD, DACLAM, and
MLAS, DVM, DACLAM
Page Range: 1 – 15
DOI: 10.30802/AALAS-JAALAS-24-126
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The soles of staff shoes accessing vivaria can become contaminated on urban streets, potentially serving as a source of fomite-mediated transmission of adventitious agents to laboratory rodents. While shoe covers may mitigate this risk, donning them can lead to hand contamination. Staff accessing our vivaria use motor-driven shoe cleaners hundreds of times daily to remove and collect particulates via a vacuum collection system from the top, sole, and sides of shoes instead of shoe covers. Shoe cleaner debris (SCD) and contact media (CM) exposed to SCD from shoe cleaners in 5 vivaria were assessed by PCR for 84 adventitious agents. SCD and CM samples tested positive for 33 and 37 agents, respectively, and a combined 39 agents total. To assess SCD infectivity, NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) and Swiss outbred mice were housed for 7 d in direct contact with SCD and oronasally inoculated with a suspension created from SCD collected from each of the 5 vivaria. Mice were tested by PCR and serology at 3, 7, 14, and 63 d postinoculation. All mice remained healthy until the study’s end and tested negative for all agents found in SCD/CM except murine astrovirus 1, Staphylococcus xylosus, and Candidatus Savagella, agents known to be enzootic in the experimental mouse source colony. In a follow-up study, the soles of 27 staff street shoes were directly sampled using CM. Half of CM was used for PCR, while the other half was added as bedding material to a cage containing NSG and Swiss outbred mice. While CM tested positive for 11 agents, all mice were healthy at 63 d postexposure and again positive for only enzootic agents. These results suggest that shoe debris might not be a significant biosecurity risk to laboratory mice, questioning the need for shoe covers or cleaners when entering experimental barrier vivaria.

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Copyright: © American Association for Laboratory Animal Science
<bold>Figure 1.</bold>
Figure 1.

Shoe cleaner debris sample without magnification.


<bold>Figure 2.</bold>
Figure 2.

Mice after exposure to shoe cleaner debris (SCD) in the vivarium shoe cleaner study. (A) Mice following initial exposure to SCD. (B) Mice at 1 wk postexposure to SCD with some of the debris integrated into the nest.


<bold>Figure 3.</bold>
Figure 3.

Mice before and after 7 d of exposure to contact media (CM) in the NYC street shoes study. (A) Mice following initial housing with CM. (B) Mice 1 wk following CM placement. Mice have created a nest using CM.


Contributor Notes

Corresponding authors. Email: palillo.1@osu.edu or ricartr@mskcc.org
Current affiliation: Center for Comparative Medicine, University of Virginia, Charlottesville, Virginia.
These authors contributed equally to this study.
Received: Nov 04, 2024
Accepted: Dec 16, 2024