(CBS) — Hand dryers in public washrooms should be a clean way to dry your hands, but are some harboring potentially dangerous bacteria?

CBS 2’s Dave Savini tested filthy-looking hand dryers.

The CBS 2 Investigators scraped, swabbed and collected grime from 12 Dyson Airblade hand dryers in the Chicago area, following the guidance and protocol set by Loyola University Medical Center’s microbiology lab.

Dr. Paul Schreckenberger and researcher Sam Collier conducted the lab tests. They found potentially harmful bacteria in most of the ones tested.

“Ten out of the 12 were grossly contaminated,” Collier says.

The 10 dirtiest machines tested were at Glenview’s Costco, the Glen of North Glenview and Union Station train stations, Fox Valley Mall, Water Tower Place and Whole Foods in Naperville.

Three more bathrooms at the Rosemont outlet mall, called Fashion Outlets of Chicago, all tested positive for large bacteria colonies.

“Very significant growth,” Collier says. “Greater than 100,000 colonies.”

Loyola University Medical Center infectious disease expert Andrew Bonwit reviewed the results. He says the lab tests revealed, among other things, two pathogens that could lead to infections: Klebsiella oxytoca and Enterobacter cloacae.

“They have the potential to be serious infections in a broader variety of people,” Bonwit says.

Klebsiella oxytoca can be found in fecal matter and can be even more harmful to those with compromised immune systems, he says.

“If you have cuts or abrasions and you get more organisms on those abrasions, you might get an infection in the skin,” Bonwit says.

Eight machines that were tested contained one or two of those human pathogens. These included two machines at Union Station and two at the Rosemont outlets; also the Glen of North Glenview station, Whole Foods, Water Tower Place and Fox Valley Mall.

Again following Loyola University Medical Center’s lab protocol, CBS 2 also tested hands that had been washed and then tested them again after drying. Half of those tests showed hands were dirtier after they were dried in the machines.

“These hand dryers are not sanitized. They are not clean, and they have the potential of putting bacteria back on your hands after we’ve dried them,” Schreckenberger says.

In fact, the Fox Valley Mall testing showed Klebsiella oxytoca on the machine and on a hand that did not have it until after it was dried.

Some companies have started getting rid of these hand dryers. Advocate Lutheran General Hospital officials say they had to remove about 20 of them because they were just too hard to keep clean.

For similar reasons, officials from Fox Valley Mall say they are also removing them.

“If they are not cleaned regularly you see the results you are going to have contaminated dryers,” Schreckenberger says.

Dyson is not responsible for keeping the machines clean, the company tells CBS 2: “The substances found are commonly encountered on high touch surfaces in washrooms including door handles, sinks, faucets, paper towel dispensers and taps. Dyson Airblade hand dryers are designed to be easy to clean and Dyson provides customers with materials, knowledge and training they need to know to keep our hand dryers clean and operating to a high standard.

Many of the places where CBS 2 tested machines told us they are reviewing their cleaning procedures. Amtrak, which owns Union Station, says it has already been phasing out the dryers.

Water Tower Place: “The safety and well-being of our guests are of paramount importance to Water Tower Place and we operate under the highest of health and safety standards. We support and cooperate fully with all health regulations while following manufacturer instructions and suggested practices.”

Amtrak: “Chicago Union Station has approximately 135,000 visitors every weekday, which equates to approximately 46 million visitors a year. Any comparison of lavatory conditions should be among those with a similar volume of visitors.

“While the current hand dryers in lavatories near the ticketing lobby and in the concourse comply with standards, we will replace them by the end of this year with those produced by another manufacturer. The current units are checked for functionality by engineering and janitorial staff daily. They are wiped down during normal restroom checks throughout the day and are cleaned nightly as part of scheduled full lavatory cleaning. The HEPA filters are changed per the manufacturer recommendation for the number of cycles.

“As the owner of Chicago Union Station Co., Amtrak is always striving to implement the best industry practices. The newest lavatories in the station use hand dryers from a different manufacturer, as will those now under construction and in the future.”

Fashion Outlets of Chicago: “We maintain very high standards for cleanliness throughout our shopping center, including our restrooms. Many new and renovated restrooms used by the public, in all kinds of settings, have incorporated this environmentally friendly technology. We appreciate this issue being brought to our attention, and we will actively explore alternatives for our shoppers visiting the restrooms.”

An official with the Village of Glenview, which maintains the train station, says they will contact Dyson representatives to come up with cleaning recommendations. The official says they will get all of these hand dryers in Glenview up to standard or remove them.