Ewww. Well you really shouldn’t be drinking soda anyways. Pass this on.
A recent study has revealed that a full 48 percent of soda fountains at fast food restaurants contain coliform bacteria — a bacteria that grows in feces. Eleven percent also  contained E. Coli.
Other opportunistic pathogenic microorganisms found included Chryseobacterium meningosepticum and of Klebsiella, Staphylococcus, Stenotrophomonas, Candida, and Serratia. Most of the identified bacteria showed resistance to one or more of 11 antibiotics tested.
While there have been few certified outbreaks over in the last ten years related to soda fountains, many incidents of food poisoning go unreported.
Sources:
 Treehugger January 7, 2010
 Int J Food Micro 2009
Always looking out,
Your Personal Trainer
in Whittier, Eric B.