There are several contributing factors to this problem, which is a HUGE problem:
1. Some doctors who overprescribe antibiotics
2. Some patients who, when ill, go to their doctor and expect to get a pill. We are a "a pill will fix it" society. We take pills for everything...always looking for the quick fix.
3. All the antibacterial stuff that is out now. You don't need antibacterial soap, mouthwash, clothes detergent etc. In the normal course of a day,the average person doesn't contact any bacteria that will kill them. This does not include people who are immunocompromised, such as cancer patiens, HIV patients, post organ transplant patients etc. I am talking about the average reasonably healthy normal American.
Right now, there are bacteria that have no known antibiotic that will work against them. I know this because I have cared for patients in the hospital who have had these bacterial infections. We give a combination of several less ideal antibiotics and hope for the best.