Bacteria experiment at MCG Microbiology Lab


We have become much more aware of all of the surfaces we touch daily and what kinds of germs can be on them.

The Microbiology Lab at the Medical College of Georgia conducted an experiment with Newschannel 6’s Ashley Osborne. She went there on a Monday and Microbiologist Dr. Allison McMullen swabbed Ashley’s phone, keys, fingers, under her fingernails and the bottom of her shoe. The goal of the experiment was to see what grew overnight so they checked back in the next day.

The cleanest surface from the experiment might surprise you and the dirtiest might as well! First, a little information from Dr. McMullen about bacteria.

“We have bacteria all over us. There is actually more bacterial cells on our bodies than there are human cells,” Dr. McMullen explains. “Those bacteria help us keep the bad bacteria away. They help break down our food. They help do a lot of different things so we have to have bacteria. There are also bad bacteria and we have a lot of bad bacteria on surfaces. Some people who do not wash their hands very well may transfer bad bacteria to those surfaces.”

Dr. McMullen also explains that some practices might not help as much as you think. For example, wearing gloves does not protect you from germs unless you remove those gloves and put on new ones in between touching things and touching yourself. Dr. McMullen says gloves are actually harder to clean than your own hands. She says you are better off carrying a mini hand sanitizer to the grocery and using it frequently, than you are shopping in gloves.

“Once [gloves] get dirty, now they’re transferring all that dirt to all sorts of different surfaces,” says Dr. McMullen. “They touch their face, they touch all sorts of things so they’re actually potentially increasing their risk of becoming contaminated with whatever they think they’re protecting themselves from.”

Back to the experiment we conducted in Dr. McMullen’s lab.

She swabbed NewsChannel 6’s Ashley Osborne’s phone, keys, fingers, under her fingernails and the bottom of her shoe.

Many of you have already shared on Facebook what you think grew the most bacteria overnight. Some of you were right, but many of you were wrong.

The surfaces that grew the most bacteria in order of most to least were as follows:

  1. Underneath the fingernails
  2. Bottom of the shoe
  3. Fingers
  4. Cell Phone

“This is a great example to show you that we miss a lot when we clean with our hand sanitizer and with our soap and water,” says Dr. McMullen. “Yu’re not getting hand sanitizer or soap and water underneath your fingernails.”

Remember how Dr. McMullen talked about good bacteria versus bad bacteria? The good news is all the bacteria that grew from reporter Ashley Osborne’s phone, keys, fingers, fingernails and shoe was your run of the mill “good bacteria.” (“Thank goodness!” -Ashley)

“Fortunately, these are all good organisms,” Dr. McMullen says about the bacteria that grew overnight from under the fingernails. “Nothing is bad under there so I’m not concerned for that, but it does go to show that there are a lot of places that we don’t think about when we’re cleaning our hands that could harbor potentially harmful organisms.”

In conclusion, this experiment shows that the advice you keep hearing about washing your hands and washing them well, really works!

Photojournalist Gary Hipps

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