Public health officials are investigating iced tea among other menu items at a Stephens County barbecue restaurant as the possible source of a major E. coli outbreak that has sickened as many as 18 people.

OnlineAthens reports 11 people have been confirmed to have E. coli infection, and seven others are probable cases, though their illness has not been confirmed by lab results, state officials say.

“The risk is gone,” said Nancy Nydam, spokeswoman for the state Department of Public Health.

“We are looking at everything on the menu,” Nydam said Friday.

Investigators are looking at the possibility of cross contamination.

Cherie Drenzek, state epidemiologist at Public Health said public health officials learned of the outbreak after a DPH epidemiology surveillance officer noticed a cluster of E. coli cases — four patients in one week — in lab reports from the Stephens County Hospital.

The Stephens County Health Department had also received complaints about the BBQ Shack after some customers reported being ill after eating at the restaurant.

Public health investigators interviewed all the patients who were sick, as well as some diners who ate at the restaurant but did not become ill, tracking them down using credit card receipts. Food samples and environmental swabs taken from the restaurant on May 16 tested negative for any pathogens.

The restaurant is cooperating in the probe, public health officials said.