Rochester, Minnesota - A new study shows an estimated 30 percent of outpatient oral antibiotic prescriptions are unnecessary. Penicillin and other antibiotics have played a leading role in treating bacterial infections, preventing the spread of disease and minimizing serious complications of disease; however, overuse of the drugs has led to antibiotic resistance.

Mayo Clinic infectious diseases specialist Dr. Pritish Tosh says, "We are seeing across the country and the world worsening issues of antibiotic resistant bacteria, meaning that we have antibiotics that are sometimes not effective against bacteria that cause infections."

Antibiotics are used to treat bacterial infections such as pneumonia and won't help viral illnesses such as colds, flu and most sore throats.

Recently, the American College of Physicians and the Centers for Disease Control and Prevention released a paper that outlines best practices for use of antibiotics. It recommends that clinicians not prescribe antibiotics for patients with a common cold.

Dr. Tosh adds, "The area where antibiotics are misused is in the treatment of upper respiratory infections. Often people have a viral cough or viral upper respiratory illness, or perhaps even a mild bacterial process that gets better on its own. It's very clear you don't need antibiotics to treat these."