Antibiotics are medicines used to prevent and treat bacterial infections. Antibiotic resistance occurs when bacteria change in response to the use of these medicines.Bacteria, not humans or animals, become antibiotic-resistant. These bacteria may infect humans and animals, and the infections they cause are harder to treat than those caused by non-resistant bacteria.Antibiotic resistance leads to higher medical costs, prolonged hospital stays, and increased mortality.The world urgently needs to change the way it prescribes and uses antibiotics.