Workers in hospitals carry strep to the hospital. Intensive care units harbor super bugs that are not destroyed by germicidal cleaning. Personnel go outside to smoke and return with outdoor bacteria. All we have to do is wipe out the enemy and we will be cleaned. Kids in day care centers are given antibiotic creams for cuts and bruises that result in super bugs.
Patients visit the doctor with a cold and insist on an antibiotic to get well fast.
Doctors comply rather than discuss the matter. Besides, it could become a malpractice issue if the patient later got pneumonia. We have been destroying good bacteria that are part of us, that help us in ways that we do not know. We have new organisms proliferate that never existed before in nature. Our body's defenses now make antibodies against our own cells.