There are two main types of germs that cause illness, viruses and bacteria. Antibiotics only fight bacterial infections. Sometimes antibiotics are given unnecessarily for infections that they will not help or cure. If you take an antibiotic when it is not necessary, such as for a cold, you increase the risk of developing an infection caused by antibiotic-resistant bacteria. Some bacteria are not killed by antibiotics.
Resistant bacteria emerge because of overuse and misuse of antibiotics.
An antibiotic-resistant infection is an infection that is difficult or impossible to cure with antibiotics. Ear, sinus, throat, lungs, and intestines are common sites for antibiotic-resistant infections. These infections may be hard to treat, resulting in longer and more severe illnesses. They may even need to be treated in the hospital. Bacteria that have been exposed to the antibiotic but have developed ways to fight them survive.