Yum Brands' second-quarter profit more than doubled, driven by higher sales that offset headwinds from a high-profile food safety crisis that emerged in recent weeks. The restaurant operator said total worldwide system sales grew 5%, excluding foreign currency translation, while same-store sales climbed 3% for the quarter ended June 30. Its Taco Bell division posted 7% growth in same-store sales, while KFC reported a 2% increase for the quarter. Taco Bell's U.S. system sales climbed 9%, while KFC's increased 6%.

The company didn't provide an update on the multi-state cyclospora outbreak that has been linked to iceberg lettuce served at some Taco Bell locations. The outbreak, which led to fewer visits to the chain, has dented shares since reports of cases emerged earlier this month. Yum shares were down 0.5% in premarket trading Thursday.