Germen was 2-0 in four scoreless appearances with Iowa this season. The 27-year-old right-hander was claimed off waivers from Texas in January. He will be available to pitch in Sunday's game against the Padres.
He pitched two seasons with the New York Mets. In 54 relief appearances, he was 1-2 with one save and a 4.31 ERA.
Szczur was 2 for 10 with one double and one RBI for the Cubs.
To make room for Germen, the Cubs placed right-hander Jacob Turner on the 60-day disabled list.