Nose tackle Aubrayo Franklin, who is listed at 317 pounds, recorded his first career interception in the second quarter when he picked off Jay Cutler at the goal line.
Franklin returned it 10 yards.
"I was pretty tired out there," Franklin said. "It had been a long drive. I tried to run with it, but I didn't have the legs left to go anywhere."
The last time the 49ers recorded more than four interceptions in a game was Sept. 14, 1997, against the New Orleans Saints. The 49ers picked off six passes that day.
In addition to Bruce, the 49ers' other inactive players were running back Glen Coffee (concussion), cornerback Nate Clements (shoulder), tackle Joe Staley (knee), defensive lineman Demetric Evans (shoulder), as well as cornerback Keith Smith, center Cody Wallace, and third quarterback Nate Davis.