They are put in bathrooms for your convenience.For a parent juggling a stroller, a diaper bag and a baby, a diaper changing table can be a lifesaver.But you could be laying your precious package down on a bed of bacteria.Call7 Investigator Theresa Marchetta did a spot check of some popular public changing tables and what she found could have you re-thinking diaper duty.I don't wipe them down. Usually, Im just trying to get her changed as fast as I can," said Jill Krug.With two, young children, Krug is used to juggling.Do you ever use the pull down tables? asked Call7 Investigator Theresa Marchetta.All of the time, Krug replied.She said she usually finds something to put down under her daughter, Alexa.Im thinking, please either let me have my changing pad or a blanket or something that I can put under her head, she said. What do you think could be potentially on there? asked Marchetta.Um, feces. And who knows, spit up and who knows what else, Krug replied."So, if I lay her down on it she would be susceptible to all the bacteria and germs," said Sarah Schepman.She uses her own changing mat under her daughter Lauren and then, sanitizes it."I wipe it down. Im pretty vigilant about wiping it down after every use. But, who knows what's left on there?" said Schepman.When you consider public changing tables are used potentially dozens of times a day, it is not hard to imagine wiggly little ones not only leaving germs behind, but also picking them up.I think, how can they be clean? With so many babies using them every day? In restaurants and airports, said Schepman.Call7 wanted to know, too.Using swabs provided by a local lab, Marchetta randomly tested changing tables for the presence of bacteria and coliforms -- in other words -- fecal matter.The swabs were returned to the lab to be processed and to count the colonies of bacteria that grew.I think I would probably be concerned about any level of bacterial contamination. Just because you dont know what bacteria is actually there, said University of Colorado Hospital infectious disease expert, Dr. Michelle Barron.Barron analyzed the test results and estimated a range of concern for the amount of bacteria present on the surfaces.Two samples tested positive for fecal matter on the changing table surface: A big box store and a library.Changing babies isn't always the easiest thing and often there is a little spillage, said Barron. We know that it can be transmitted from these surfaces to other people. Sometimes through hands or contact with open skin."All of the samples contained some level of bacteria.On the lower end, with a number fewer than 10, places many might not expect: a rest stop, the same big box store that had fecal coli forms, and a fast food restaurant.In the middle range, with numbers between 10 and 100: a city building, the same library that had fecal coliforms, 3 mall restrooms and an airport.Some of them (bacteria) may be associated with skin which wouldn't be harmful. Some of them may be harmful and it is not clear based on this. Its still worrisome that they have that much bacteria, said Barron.In the high range, over 100, some surprises: a hospital, another big box store, and a coffee shop.The ones that had very high counts of bacteria, you really question how well the surface is actually cleaned, or if it was cleaned at all, said Barron.There have been cases of surface contamination with salmonella, shigella, things that are obviously quite concerning.The nasty germs could cause serious illness when coming in contact with the baby and parent or caregiver."While you are changing you end up itching something, cell phone rings, all sorts of other things can become contaminated in the process," Barron said.Call7 also tested the changing pads moms' carry with them.One was in the low range for bacteria at 7.The other was in the moderate range at 22.Would you do anything differently? Marchetta asked Krug.I would probably wipe it (the changing mat) down more or put it in the laundry. Or use the disposable ones, Krug said.Whatever your strategy, Barron said do not assume because a surface looks clean, that it is.You can't rely on anybody else making sure its clean for you, said Schepman. Call7s test results may not necessarily reflect inadequate cleaning.No one knows who used a changing area before the next person arrived.Marchetta found some businesses, like The Cherry Creek Mall, are being proactive by providing disposable changing pads, wipes and sanitizer at their changing stations.Barron said there is no substitute for frequent hand washing to stop the spread of germs, but adds, a clean barrier is another critical step in protecting a child from illness.