The following is an excerpt from the FDA web site:
Disease-causing microbes that have become resistant to drug therapy are an increasing public health problem. Tuberculosis, gonorrhea, malaria, and childhood ear infections are just a few of the diseases that have become hard to treat with antibiotic drugs. Part of the problem is that bacteria and other microorganisms that cause infections are remarkably resilient and can develop ways to survive drugs meant to kill or weaken them. This antibiotic resistance, also known as antimicrobial resistance or drug resistance, is due largely to the increasing use of antibiotics. Other facts:
Though food-producing animals are given antibiotic drugs for important therapeutic, disease prevention or production reasons, these drugs have the downside of potentially causing microbes to become resistant to drugs used to treat human illness, ultimately making some human sicknesses harder to treat. About 70 percent of bacteria that cause infections in hospitals are resistant to at least one of the drugs most commonly used to treat infections. Some organisms are resistant to all approved antibiotics and must be treated with experimental and potentially toxic drugs.
Some research has shown that antibiotics are given to patients more often than guidelines set by federal and other healthcare organizations recommend. For example, patients sometimes ask their doctors for antibiotics for a cold, cough, or the flu, all of which are viral and don’t respond to antibiotics. Also, patients who are prescribed antibiotics but don’t take the full dosing regimen can contribute to resistance. Unless antibiotic resistance problems are detected as they emerge, and actions are taken to contain them, the world could be faced with previously treatable diseases that have again become untreatable, as in the days before antibiotics were developed.