A culture attributed the infection partly to ESBL E. coli. Doctors inserted a tube to administer an intravenous antibiotic in an effort to save his life.

Image Nicholas D. Kristof Credit... Fred R. Conrad/The New York Times

If ESBL E. coli is frightening, there are even more potent superbugs emerging, like Acinetobacter.

“We are seeing infections caused by Acinetobacter and special bacteria called KPC Klebsiella that are literally resistant to every antibiotic that is F.D.A. approved,” Dr. Spellberg said. “These are untreatable infections. This is the first time since 1936, the year that sulfa hit the market in the U.S., that we have had this problem.”

The Infectious Diseases Society of America, an organization of doctors and scientists, has been bellowing alarms. It fears that we could slip back to a world in which we’re defenseless against bacterial diseases.

There’s broad agreement that doctors themselves overprescribe antibiotics  but also that a big part of the problem is factory farms. They feed low doses of antibiotics to hogs, cattle and poultry to make them grow faster.

A study by the Union of Concerned Scientists found that in the United States, 70 percent of antibiotics are used to feed healthy livestock, with 14 percent more used to treat sick livestock. Only about 16 percent are used to treat humans and their pets, the study found.

More antibiotics are fed to livestock in North Carolina alone than are given to humans in the entire United States, according to the peer-reviewed Medical Clinics of North America. It concluded that antibiotics in livestock feed were “a major component” in the rise of antibiotic resistance.

Legislation introduced by Louise Slaughter, a New Yorker who is the only microbiologist in the House of Representatives, would curb the routine use of antibiotics in farming. The bill has 104 co-sponsors, but agribusiness interests have blocked it in committee  and the Obama administration and the Senate have dodged the issue.