WASHINGTON-The Food and Drug Administration is intensifying its focus on problems caused by antibiotic resistance among humans and feed animals through the widespread use of those drugs over the past several decades, said FDA Commissioner Margaret Hamburg.

Appearing at the National Press Club Wednesday, Dr. Hamburg said the FDA is seeing antibiotic resistance in virtually all antibiotics.

“We no longer have effective ways to treat serious infectious disease. Clearly we must encourage more judicious use of these important drugs,” she said.

The drugs have been almost routinely used in recent years for common colds and ear infections in children, and have become fairly standard additions to feed in chicken houses and for livestock, which are then eaten by consumers. The result has been the growth of bacteria and life-threatening diseases that respond poorly, if at all, to even some of the most modern antibiotic treatments.

Dr. Hamburg said the research and development pipeline for new drugs in general is “distressingly low” and said that is true of antibiotics in particular. “The range of new antibiotics is disturbingly limited,” she said.

The agency has been discussing internally, and with consumer health groups and the food industry, standing regulations regarding the use of antibiotics in animal feed and guidelines on antibiotic use for patients.