The problem is that antibiotics work only against infections caused by bacteria. Antibiotics cannot cure the common cold or even the flu, both of which are caused by viruses. But that doesn't keep patients from demanding them. So, we are our own worst enemy in this. Antibiotic resistant infections can be spread from one person to another.
Hospitals are well known breeding grounds, especially if medical personnel fail to wash their hands.
But no one can be sure exactly how each infection is transmitted. After Tabitha Gerrard had gall bladder surgery, she developed a resistant infection. She was sent to Vanderbilt University Hospital for treatment. After 3 weeks, doctors finally found a combination of drugs that cured her. She was one of the lucky ones.