Here is some stuff I've found throughout the internet about "salmonella-free" turtles:
Most, if not all, reptiles carry Salmonella in their intestinal tract and intermittently or continuously shed these bacteria in their feces.
Furthermore, turtles only shed Salmonella intermittenly, so a negative test is unreliable. A secondary concern is the accidental production of antibiotic resistant Salmonella instead.
Cases have been documented where "Salmonella-free turtles" turned out not to be Salmonella-free, after all. But even the original research stated that a small percentage of treated eggs / hatchling were not free of Salmonella. There is also a lack of recent peer-reviewed research to prove the efficacy of the procedures used to produce Salmonella-free turtles.
Salmonella is very common in many cold-blooded animals, including turtles. This germ can be carried by both land and water turtles. Not all turtles have the bacteria, but they can carry Salmonella without getting sick.
You can find more info at peteducation.com, about.com, newton.dep.anl.gov, to name a few. Hope this information is helpful.
My babies: Tanner (RES), MR. Prissy & Ringo (budgies), Shinju (cockatiel)
"Little dudes are just eggs, we leave 'em on the beach to hatch, and then — koo-koo ka-choo! — they find their way back to the Big Ol' Blue"