Why are we told not to take antibiotics if we don't need them, but some doctors give them to prevent infection, like with surgery?

Overuse of antibiotics has caused a problem with bacteria getting resistant to the medications we have. However, giving prophylactic antibiotics, antibiotics that prevent infection from happening in the first place, is a different situation.

Over the years of providing certain types of treatments or surgeries, doctors and researchers learn what common complications occur and they work to prevent them. One common complication of different types of surgeries is infection. Infection in the spine, for example, can cause serious complications, so it's important to do everything you can to avoid this.

Other than the standard sterile techniques and good surgical technique, one way to prevent infections that are common to the surgery is by treating the patients to prevent the bacteria from settling in to begin with. These antibiotics must be the right ones for the particular type of bacteria they are trying to prevent from entering and they are only to be taken for the set prescribed time.