It seems that no food is perfectly safe from unwelcome microscopic guests, not even those delicious crème-filled cookies you accidentally binged on at the holiday party.

According to a recent study published earlier this October in the Journal of Food Protection, a bacteria commonly responsible for foodborne illness, Salmonella, can survive for at least 6 months in certain fillings used for cookie and cracker sandwiches. Though Salmonella outbreaks have previously been traced to dry food products, the study reaffirms the germ’s hardy durability in places most had assumed it couldn’t last long in.

“The ability of Salmonella to survive for at least 182 days in fillings of cookie and cracker sandwiches demonstrates a need to assure that filling ingredients do not contain the pathogen and that contamination does not occur during manufacture,” concluded the authors.

Salmonella is one of the most commonplace foodborne bugs to disturb our stomachs, with an estimated 80 million cases of food poisoning occurring annually worldwide. Like most every other living thing, though, Salmonella thrives best in an environment with ample water. That’s generally left food manufacturers free to assume that processed products with little moisture, such as ready-to-eat meals or crackers, were largely inhospitable to the germ.

But while Salmonella would rather not call a dry cracker their new summer home, that doesn’t necessarily mean it can’t hunker down and bide its time until it ends up somewhere more comfortable — like our bellies.

To test out its staying power, the researchers of the current study gathered together strains of Salmonella previously implicated in dry-food outbreaks and introduced it to four different types of cookie and cracker filling. These were chocolate and peanut butter crème for the cookies and peanut butter and cheese for the crackers. They also tested it out on vanilla and chocolate cookie dough, as well as cheese cracker dough. The samples were given different amounts of Salmonella, using either a dry or wet method of inoculation. Finally, they were placed in room temperature storage and periodically checked in on until they reached 182 days, or 6 months.

Across all the samples, Salmonella survived some length of time, though it appeared to have favorites among the crowd. "The salmonella didn't survive as well in the cracker sandwiches as it did in the cookie sandwiches," study author Professor Larry Beuchat explained in a statement. The samples of chocolate crème and peanut butter crème fillings, for instance, allowed the germ to survive the full six months. "That was not expected," said Beuchat, who is a researcher at the University of Georgia’s Center for Food Safety.

Having now demonstrated that Salmonella can endure in these products, Beuchat and his colleagues hope to hone in on its preferred hiding places, since curtailing or replacing specific ingredients may prevent the germ from ever taking hold to begin with. "The next steps would be to test all ingredients that are used in these foods," he said.

Source: Beuchat L, Mann D, Survival of Salmonella in Cookie and Cracker Sandwiches Containing Inoculated, Low–Water Activity Fillings. Journal of Food Protection. 2015.