Responding to concerns about bacteria build-up in countertops, NBC's television affiliate in St. Louis, MO, KSDK, conducted independent testing that confirmed granite as a premium building material in terms of anti-bacterial and cleanability qualities.

Using a sterile kit, KSDK reporters swabbed the most used sections of a residential countertop, and they also swabbed crevices where bacteria could build up. The sample was then taken to Microbe Inotech, a nationally accredited facility in St. Louis, where it was tested for bacteria, yeast and mold.

"There were 10 isolates from the very first dilution, " Microbe Inotech microbiologist Theresa Joseph told KSDK. "That means there was one small colony of bacteria, and an insignificant amount of yeast and mold. I would give credit for a clean kitchen."

The KSDK report also cited a report that can be found on the Marble Institute of America's Web site that shows granite as the top material in terms of cleanability. The test was conducted by the Hospitality Institute of Technology and Management, and after washing and rinsing, the granite tops provided the greatest reduction in bacteria counts of all the materials tested:  
  • Granite: 36,000 to 1
  • Stainless Steel: 4,000 to 1
  • Concrete: 2,400 to 1
  • Tile: 900 to 1
  • Wood: 500 to 1
  • Plastic Laminate: 285 to 1
For more information on the report, visit:

To read the KSDK report, visit: