Image
© Brian Merchant/foodfreedom
The soda that comes out of fountain machines in restaurants may be widely contaminated with fecal bacteria, according to a study conducted by researchers from Hollins University and published in the International Journal of Food Microbiology.

Researchers tested 30 different self-serve and behind-the-counter soda machines at a variety of restaurants in Virginia's Roanoake Valley for the presence of so-called coliform bacteria, or bacteria that are commonly found in mammal feces. They found that 70 percent of beverages sampled tested positive for some form of bacteria, and 48 percent tested positive for coliform bacteria.

"The EPA regulates our drinking supply, and there can be some bacteria, but one of the things that is not allowed is coliform bacteria," researcher Renee D. Godard said. "We can't have that in our drinking supply. But they're coming out of these soda fountain machines."

Twenty percent of beverages tested positive for levels of coliform bacteria exceeding drinking water standards.

The researchers could not uncover the source of the contamination, but concluded that it probably came from the machines rather than the water (which tested negative for bacteria) or the beverage companies (multiple brands were infected). All restaurant managers interviewed said they cleaned the fountain nozzles daily.

"Our best guess is they're actually establishing themselves on the lining of the plastic tubing," Godard said. "In other areas, such as hospitals, it is known that bacteria can establish themselves on plastic tubing for machines."

Only one restaurant manager reported regularly cleaning out the machines' plastic tubing.

No health outbreaks have ever been traced to soda machines, and the researchers and other microbiologists noted that the risk of contracting a disease from a fountain drink is probably low. The high prevalence of the contamination is still an element of concern, however, because it suggests that the soda machines could become breeding grounds for dangerous strains of viruses or bacteria, including drug-resistant varieties.

Microbiologist Philip Tierno of New York University said he was not surprised by the findings.

"Wherever man is there will be representation of feces," Tierno said. "We're basically bathed in feces as a society."