In a large skillet, cook the bacon over medium heat for 5 minutes. add the onion, celery, bell pepper and garlic and cook until the vegetables are softened, about 7 minutes; push to the side of the skillet. Increase the heat to high, add the ground beef and cook, stirring to break up any clumps, until cooked through, about 7 minutes. Stir in the ketchup and Worcestershire sauce and cook until thickened, about 5 minutes more. Season to taste with salt and pepper and serve on the toasted buns.