Last year, Americans spent more than $170 million on hand sanitizers alone.

So we wondered what works best and how to the sanitizers comparing a showdown with soap.

Well, tonight, our chief medical editor, Dr Richard Besser, puts them to the test and get some real answers.

Clean as many as 400,000 germs.

Her hand.

That's how many bacteria travel with us every day.

So you're at the University of Maryland Food Saiki Lab.

Six brave grad students and I voluntarily doused her hands in a toxic brew of thousands of E.

Coli bacteria.

Yep, E.

Coli Good.

Something that a little odd about rubbing cola to see what would take it off first up hand sanitizers.

We tested two kinds you'll find at the store.

One with 60% alcohol and one so called natural formula containing no alcohol key with hand sanitizers is to use it.

Enough of it.

Your hands should take a full 15 seconds or longer to dry.

Now let that air dry.

Okay, then we pressed our hands onto special incubation plates to grow any remaining bacteria.

The results dramatic here.

Those graying spots of the coli that grew from unwashed hands after using hand sanitizer with 60% alcohol.

But the formula without alcohol.

Just look at how many germs are left behind.

Alcohol based hand sanitizers works so much better because alcohol breaks up the bacteria's proteins and kills them.

But if you really want to get clean, what's your best bit of all?

Guess what?

It's your old friend, so so not only does as well in bacteria is the sanitizer.

It gets more viruses too.

Surprising studies show regular end into bacterial soap are about equally effective, but how you use it is crucial.

Go.

Most of us only spent five seconds in the sink.

Just look how many germs remain.

Yuck!

Go.

You have to wash your hands for a full 20 seconds to really get the bugs off on.

And yet that singing Happy Birthday twice.

So let's review it again.

Hand sanitizers.

If you can't get to a Cinque, look for one with at least 60% alcohol but washing with soap.

Any kind is better, as long as you watch for long enough.

Dr.