Wheel Contact Test
For the Wheel Contact Test, the request is the removal efficiency of environmental microbes from cart wheels using VWR Collection peel-off mats.

Materials

• Gray peel-off mats, 45”x 26”, 30 per stack
• Plastic wheels from utility cart
• Culture plates containing tryptic soy agar (TSA)
• Presaturated alcohol wipes

Test Method
A preliminary test was performed to identify a suitable surface for conducting the study.  The most suitable surface was one with a microbial population which was large enough to be statistically valid, but not so large that colonies overlapped on the culture plates. A variety of substrates and indoor areas were selected for this preliminary test.
In the performance of the preliminary test, cart wheels were sanitized using nonwoven wipers presaturated with 70 % isopropyl alcohol. The wheels were rolled along a 5-inch length of the dirty floor, then rolled along the surface of a culture plate containing tryptic soy agar (TSA). Plates were incubated for five days at 30 –35 degrees C and colony-forming units (cfu) counted. The most suitable test surface was selected based on total microbial counts and colony growth patterns.
Location F was selected for conducting the final testing. Two clean sanitized cart wheels were rolled along the floor side-by-side for a distance of 10 inches. One cart wheel was then rolled along the surface of an agar plate containing tryptic soy agar (TSA). The second wheel was rolled over the width (26”) of a peel-off mat, then rolled along the surface of an agar plate. Two additional test runs were performed. Plates were incubated at 30 –35 degrees C for 48 hours and colony-forming units were counted. Microbial removal efficiencies were calculated.

Conclusion
97 % of the viable microbes picked up by plastic cart wheels from a dirty floor were removed by rolling the wheels across the width of the peel-off mat.

Wheel Airborne Test
For the Wheel AirborneTest the request is to determine if the use of VWR Collection peel-off mats will reduce the number of viable microbes present on cart wheels, as determined through airborne testing.

Materials

• White peel-off mats, 18”x 36”, 30 per stack
• Plastic wheels from utility cart
• Stainless steel platform, perforated, 12”x 12”
• Culture plates containing tryptic soy agar (TSA)
• Presaturated 70 % isopropyl alcohol wipes

Test Method
In step 1, four cart wheels were sanitized using nonwoven wipers presaturated with 70 % isopropyl alcohol to remove any preexisting contamination.
In step 2, the clean cart wheels were rolled along the base of a 10-inch length of a glass dish containing a heavy dusting of fresh dirt to ensure that each wheel picks up a sufficient amount of dirt for testing.
In step 3, two of the cart wheels were rolled along an 18” length of a fresh peel-off mat. The other two wheels did not contact the mat.
In step 4, each cart wheel was rolled along the surface of a perforated stainless steel platform with three open culture plates located below the platform (Referred to as Plate # 1, Plate # 2, and Plate # 3 in results table).
In Test #1 — one wheel was rolled across the platform once. In Test # 2 — The other wheel was rolled across the platform twice.
In step 5, plates were incubated for two days at 30 –35 degrees C and colony-forming units (cfu) were counted.

Conclusion
The test results indicate that rolling a cart with contaminated wheels across a peel-off mat will reduce the level of viable microbes released into the air by > 99 %.