Complex sentence: Antibiotics, especially those with a broad spectrum of activity (such as clindamycin) cause disruption of normal intestinal flora, leading to an overgrowth of "C. difficile", which flourishes under these conditions.
Split into simpler sentences: Antibiotics, especially those with a broad activity spectrum (such as clindamycin) disrupt normal intestinal flora. This can lead to an overgrowth of "C. difficile", which flourishes under these conditions.