Effectiveness of shoe covers for bioexclusion within an animal facility

The personal protective equipment (PPE) required for entry into rodent barrier rooms often includes a hair bonnet, face mask, disposable gown, gloves, and shoe covers. Traditionally, shoe covers have been considered essential PPE for maintaining a 'clean' animal room. The introduction of microisolation caging and ventilated rack housing prompted us to reevaluate the contribution of shoe covers to bioexclusion. Contamination powder that fluoresces under black light was to track particle dispersal on the floor and personnel. The test mouse room contained a ventilated microisolation rack and biosafety cabinet. Powder was applied directly inside or outside the animal room doorway. PPE with or without shoe covers was donned outside of the animal room doorway and discarded on exiting. Participants either were scanned on entry into the room for the presence of florescence or asked to complete a simulated standard animal room activity while wearing full PPE. Animal rooms were scanned for florescence after exit of participants. All participants donning shoe covers fluoresced in multiple areas, primarily on gloves and gowns. Shoe covers had no effect on the spread of powder in normal traffic patterns, with no powder detected within caging. Powder also was used to determine the distance substances could be carried on the floor from building entry points. Results indicate that shoe covers do not improve (and actually may compromise) bioexclusion. Donning of shoe covers offers a potential for contamination of personnel from contact with shoe bottoms.