Antibiotic resistance has been called one of the world’s most pressing public health problems. Almost every type of bacteria has become less responsive to the antibiotic treatment designed to combat it. And antibiotic resistance affects everyone’s health in a way that no single disease does. It is a particularly serious problem for patients whose immune systems are compromised, such as people with HIV/AIDS and patients in critical care units. Resistant pathogens lead to higher health care costs because they often require more expensive drugs and extended hospital stays.