PORTLAND, Ore. -- During cold and flu season, having clean hands is one of the most important steps you can take to avoid getting sick. So, which is better: washing with soap and water or hand sanitizer?

To find out, we conducted a test at the Providence Regional Microbiology Lab in Portland.

Pathologist Dr. Margret Oethinger doused my hands with a nasty brew of E. coli. Then, I dabbed my germ-infested hand onto an incubation plate.

For the first test, I used just a small amount of hand sanitizer. It was about the size of a dime. I rubbed the hand sanitizer around on my hands until it was dry on the skin. Then, I dabbed the petri dish.

Pathologist Dr. Margret Oethinger doused my hands with a nasty brew of E. coli.

After washing thoroughly, we repeated the exercise. That meant more E. coli. This time I used a lot of hand sanitizer: three pumps from the dispenser. It was literally dripping from my hands. It took some time for the alcohol-based sanitizer to dry.

The next test involved washing with soap and water. We repeated the steps: First, I washed thoroughly, then doused my hands with the E. coli mixture. This time, I washed with soap and water. It was brief, probably about the length of time most people spend at the sink. I rubbed the soap around, then rinsed and dried with paper towels.

The final test involved serious washing. I followed our same routine. This time, I washed with soap and water for nearly 30 seconds. I scrubbed every finger, around the nails and the front and back of both hands. They felt really clean.

Dr. Oethinger placed the samples in an incubator at the lab. Then, 24 hours later, we returned to see the results.

Heavy hand sanitizer was most effective. The incubation plate showed little growth when I used a lot of hand sanitizer.

“The hand sanitizer would have an advantage,” explained Dr. Tobias Pusch, an infectious disease specialist at Providence Health & Services.

The Centers for Disease Control and Prevention recommends alcohol-based hand sanitizer that contains at least 60 percent alcohol. You should put enough sanitizer on your hands to cover all surfaces.

“As long as you have the product in your hand you want to keep your hands wet until it slowly dries out,” said Dr. Pusch.

Heavy hand washing with soap and water was also effective, although it showed some E. coli growth on the incubation plate.

“Regular hand-washing with soap doesn’t necessarily kill the bacteria off, it’s more mechanical, cleansing,” explained Dr. Pusch.

Hand washing reduces the amounts of all types of germs, pesticides and metals on your hands according to the CDC.

Health experts suggest you scrub all surfaces of your hands for 20 seconds. A good way to reinforce good hand-washing is to hum the “Happy Birthday” song twice.