Polypeptide antibiotics are a class of antibiotics made up of long chains of amino acids, known as polypeptides. They are effective against a variety of bacterial infections by disrupting the bacterial cell membrane or inhibiting cell wall synthesis. Common examples include Bacitracin and Polymyxin B, which are often used topically to treat skin infections. These antibiotics are particularly useful for treating infections caused by gram-positive bacteria and some gram-negative bacteria. However, their use is limited due to potential toxicity and the development of resistance. They are typically reserved for specific clinical situations where other antibiotics may not be effective.