Monday, February 1, 2010

E. Coli in the fountain soda supply?

Someone once told me, that you could tell how clean a restaurant or gas station is, by how clean its bathroom is. Thanks to this person’s statement, I now have to take a peak in any bathroom before I sit down for dinner.
Some may call me crazy, but I can’t help wonder and pray when I go somewhere to eat that the cook or lady filling the fountain machine has washed his or her hands in the last 24 hours.
The below Times article, does not help put my wondering mind at ease. The article analysis 90 soda fountains to find if they were dispensing more than fizzy beverages.

E. Coli in the fountain soda supply?

Soda fountains may dispense more than Diet Coke and Dr. Pepper, according to new research to be published this month in the International Journal of Food Microbiology. In an analysis of 90 soda and water samples taken from fountains in 30 different fast food restaurants in the Roanoke Valley region of Virginia, researchers from Hollins University found that 48% tested positive for coliform bacteria, or bacteria found in human and animal feces, 11% tested positive for Escherichia coli, and more than 17% tested positive for Chryseobacterium meningosepticum, which has been shown to cause pneumonia and even meningitis in people with compromised immune systems. So, how are these microbes ending up in our cokes? And, what does it mean for public health?

According to standards established by the Environmental Protection Agency (EPA), the public water supply cannot have a heterotrophic plate count (HPC)—or basic concentration of microorganisms—higher than 500/ml. (In Europe, the standard is 100/ml.) Yet, the researchers point out, there are no government regulations in place for the liquids dispensed from soda fountains. In this study, 20% of water and soda samples had HPC counts higher than 500/ml.
So, how are those bugs getting into the soda supply? As part of the study, researchers observed people using soda fountains to determine whether bacteria might be introduced by touching nozzles with their fingers. But, of the 281 people observed, only 5 (or 1.8%), actually nudged the nozzles. What's more, even people who got refills seldom touched the nozzles with their used cups—only 2 of 47 (or 4.2%). Amy S. White, a biologist at Hollins and lead author of the study, says she was surprised. "That was our first guess. I would have guessed that this was hand-touching—I thought that kids or people were putting their hands on the nozzles, but it's actually a really small population."

Understanding how the bacteria enter the soda fountain is key, White says, because once it's introduced, it can thrive and multiply in what is effectively a closed system. In the study, White and colleagues found that soda samples collected in the morning had far higher levels of bacterial contamination than those collected later in the day, something she hypothesizes likely has to do with the fact that, overnight, as the plastic tubes feeding the fountain aren't being regularly flushed, bacteria can take hold and grow. "What we think is happening is that there are communities of bacteria living in those tubes inside those machines—a biofilm," she explains. "As the machine gets used, the top layers of the biofilm get washed out." But, when few people are buying sodas, the liquid isn't being flushed through the tubes. "Overnight they multiply—and most bacteria can double every 20 minutes—so it doesn't take long for a whole lot of organisms to grow."

If it isn't likely down to customers putting dirty fingers on the nozzles, though, what could be introducing the bacteria that ultimately may be creating this biofilm? White and colleagues confirmed that the municipal water supply met all EPA regulations, and that there were no outbreaks during the study period, so the bacteria wasn't likely coming from the water. And sodas purchased in plastic bottles that were tested as controls showed no microbial contamination, so it wasn't likely the syrup. Previous research had found similar problems—where clean water entered a fountain but contaminated water came out—leading White and colleagues to believe that it was in fact the soda fountains, but where were these bacteria coming from?

Read the full article:

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