Complex sentence: Acne treatment was again modified in the 1950s with the introduction of oral tetracycline antibiotics (such as minocycline), which reinforced the idea amongst dermatologists that bacterial growth on the skin plays an important role in causing acne.
Split into simpler sentences: Acne treatment was modified in the 1950s with the introduction of oral tetracycline antibiotics (such as minocycline). These reinforced the idea amongst dermatologists that bacterial growth on the skin plays an important role in causing acne.