The White Sox called up Bummer from Triple-A Charlotte on Thursday, Colleen Kane of the Chicago Tribune reports.
The 23-year-old left-hander compiled a solid 3.00 ERA in 33 innings with Double-A Birmingham, accompanied by 34 strikeouts and 16 walks. Bummer will occupy a depth role for a club suddenly lacking reliable high-leverage relievers, considering the White Sox traded David Robertson, Tommy Kahnle, Anthony Swarzak and Dan Jennings in the last week or so.