It's no secret that money is dirty, but an associate professor at St. Petersburg College is conducting a study to find out which type of currency is spreading the most harmful types of bacteria.

"Not only is there a difference between the paper money and plastic currency, but there's also a difference in where we collect the paper money from," Dr. Shannon McQuaig said.

McQuaig and a small group of students who volunteered for the project called "cash or credit: spreading the wealth of virulence genes," said they discovered the bacteria MRSA on both cash and credit cards.

McQuaig said 80 percent of the dollar bills gathered from non-hospital areas had MRSA and 50 percent of credit cards also tested positive.

"We want the public to know that credit cards aren't as clean as you think they might be," McQuaig said.

"I really didn't think that it would be on as many credit cards and dollar bills as we're finding," biology student Rich Nichols said.

But, so far, the study shows that cash coming from health care workers or hospital cafeterias is much cleaner.

"We're finding about 20 percent of the dollar bills that we're collecting from hospitals are contaminated with methicillin-resistant Staphylococcus - also more affectionately known as MRSA," McQuaig said.

"We've found that most of the hand soaps in hospitals contain an anti-microbial compound called triclosan and triclosan actually kills bacteria. So they're washing their hands and then touching the money and it's not getting as contaminated."

McQuaig said she decided to focus on MRSA because it's resistant to antibiotics such as penicillin and methicillin and can be extremely problematic for people with weak immune systems.

"A majority of the population actually does carry MRSA on their skin and in their nasal cavities," she said. "And it usually doesn't cause too much of a problem. You just want to worry about spreading this to people who have a compromised immune system."

Still most people were grossed out when a reporter told them about the results of the study after they used cash or credit to pay for goods at a St. Petersburg gas station.

"I think it's disgusting because no one really has the time wash their hands after every time they go in their wallet," Rita McGregor said.

"I think that's kind of scary," Amy Koucky added.

"That's gross and I don't want to touch it," said Sade Jeanniton.

McQuaig said she was awarded a $3,500 faculty grant from SPC in December for the project.

"It enabled us to purchase all the supplies that we would need to start off the project and get it rolling," she said. "DNA extractions, all this molecular biology. ... It's very expensive stuff to do."

The associate professor also wanted to work on a project that would engage her students in microbiology research.

"This is student enrichment," she said. "They're learning how to be responsible in the lab, they're learning how to take notes, they learning how to do all this molecular biology."

Nichols, a junior at SPC, said he's grateful to work on the dirty money study.

"My goal is to be a physician assistant in infectious disease and this helps me to get a good base of knowledge on dealing with infectious disease," he said.

The "cash or credit" project began in January and so far 80 samples have been tested. The study will wrap up in December and McQuaig hopes to publish the results.