Stuart B. Levy, a physician and microbiologist who sounded the alarm on the dangers of antibiotic resistance, demonstrating that drugs routinely given to fatten farm animals posed a threat to human health, died Sept. 4 at his home in Boston. He was 80.

He had Parkinson’s disease, said his daughter, Suzanne Levy Friedman.

Long before “superbugs” became a buzzword for drug-resistant bacteria, Dr. Levy was researching and drawing attention to the issue of antibiotic resistance, which the World Health Organization labeled a “major threat to public health” in 2014. In the United States, at least 2 million people get an antibiotic-resistant infection each year, and at least 23,000 die, according to the Centers for Disease Control and Prevention.

For decades, much of the country’s antibiotics have gone to farm animals, helping chickens, turkeys, cows and pigs grow bigger and better.

In a much-cited 1976 paper, Dr. Levy found that chickens raised on feed with low doses of antibiotics developed drug-resistant bacteria that were then transferred to farmers, posing a significant health risk.

“For many years he was a voice in the wilderness, talking about things that were not a part of the conventional wisdom,” said Martin J. Blaser, a Rutgers University microbiologist. “When people like Stuey said, ‘We’re wasting our precious patrimony for a few dollars,’ the [agriculture] industry stonewalled it. He was up against Goliath.”

Dr. Levy was based at the Tufts University School of Medicine in Boston, where he taught for 47 years before retiring in 2018, and displayed a literary and artistic side that complemented his immersion in medical science. An English major in college, he struck up a correspondence with Samuel Beckett and met the playwright in Paris. Later, on what his daughter recalled as a trip to Africa, he saw someone playing the ukulele and decided to learn the instrument, strumming his own songs during academic meetings.

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Trained as a hematologist, Dr. Levy continued to see patients decades after beginning his work on antibiotics, invariably greeting them in his white coat and bow tie. His career bridged research and activism: Seeking to translate his findings into public policy, he met with regulators and politicians, discussed antibiotics on TV with Bryant Gumbel and Dan Rather, and wrote a popular 1992 book, “The Antibiotic Paradox: How Miracle Drugs Are Destroying the Miracle.”

He also formed the nonprofit Alliance for the Prudent Use of Antibiotics and, in 1981, persuaded 147 scientists from 27 countries to sign a statement on antibiotic misuse, according to Scott H. Podolsky, a Harvard professor of global health and social medicine.

“It was Dr. Levy who catalyzed the transformation of antibiotic resistance into a shared, global concern, mandating global collaborations across various domains of medicine, science, industry, agriculture, and politics,” Podolsky said by email.

On Capitol Hill, Dr. Levy met with legislators such as Rep. Louise M. Slaughter (D-N.Y.), a microbiologist who repeatedly introduced legislation to restrict the use of antibiotics in healthy cattle.

His efforts found mixed success. Slaughter’s bill never passed (she died last year), but in 2013, the FDA began phasing out the use of certain antibiotics for farm animals. Two years later, President Barack Obama announced a $1.2 billion initiative to identify emerging superbugs and increase funding for new antibiotics and vaccines.

Dr. Levy did not oppose antibiotics outright but advocated what he described as “prudent use” of the drugs, which were developed in the early 20th century and popularized in the 1940s, when penicillin entered widespread use. Antibiotics were a powerful new tool against once-deadly infections, and they were soon used in livestock feed.

By the early 1960s, scientists including Tsutomu Watanabe had identified bacteria that were newly resistant to the drugs and that spread antibiotic-resistant genetic material among themselves and even to different species.

Dr. Levy met Watanabe while in medical school and traveled to Tokyo in 1964, spending a summer in the Japanese researcher’s lab and collaborating with him on several papers. Turning his focus to antibiotic resistance, he conducted his best-known work while sponsored by an unlikely partner, the Animal Health Institute, a trade group that was hoping to demonstrate the effectiveness of antibiotics on farms.

In 1974, at 36, he devised a study that drew on the feces of 300 Leghorn chickens raised near Boston — as well as fecal samples from six local families. “We’re asking you all to be part of an experiment,” he told them over hot dogs and hamburgers, according to Maryn McKenna’s book “Big Chicken.” “We’d like you to donate something that you have to science. Frankly,” he continued, “we need your s---.”

The families obliged, and the results — published in the New England Journal of Medicine — disappointed his sponsors and surprised even Dr. Levy. “These data speak strongly against the unqualified and unlimited use of drug feeds in animal husbandry,” he wrote with his two co-authors, “and speak for reevaluation of this form of widespread treatment of animals.”

Months later, in 1977, Food and Drug Administration Commissioner Donald Kennedy attempted to ban the use of growth-promoting antibiotics. That effort was quickly halted under pressure from industry groups and pharmaceutical companies, which said there were gaps in the research.

“Our study from 1976 was [and still is] the only prospective U.S. study on this, and industry didn’t want more studies,” Dr. Levy told the Scientist magazine in 2015. “They were upset that our data showed them to be wrong. This was highly political.”

Stuart Blank Levy was born in Wilmington, Del., on Nov. 21, 1938. His mother was a homemaker, and his father was a physician who conducted house calls, sometimes taking payment in the form of produce from local farmers.

All three of the Levy children went into medicine. Dr. Levy’s identical twin brother, Jay A. Levy, is a cancer and AIDS researcher at the University of California at San Francisco, where his lab was one of the first groups to isolate HIV; his sister, Ellen Levy Koenig, also studies the AIDS virus.

The brothers were close enough that they executed an unannounced identity switch for one week in college, with Stuart attending Wesleyan University in Connecticut while Jay took his place at Williams College in Massachusetts, where Dr. Levy graduated in 1960.

Dr. Levy received a medical degree from the University of Pennsylvania in 1965, completed his residency at Mount Sinai Hospital in Manhattan and performed postdoctoral research at the National Institutes of Health in Bethesda, Md.

In 1971, he became a professor at Tufts, where he directed the Center for Adaptation Genetics and Drug Resistance. He was president of the American Society for Microbiology and wrote more than 300 papers, including an influential 1978 study that identified the role of “efflux pumps” in antibiotic resistance.

With Walter Gilbert, a Nobel Prize-winning biochemist, he also founded a pharmaceutical company, Paratek, to develop new antibiotics.

Survivors include his wife of 35 years, the former Cecile Pastel, a French-born dermatologist who lives in Boston; three children, Suzanne Levy Friedman of Washington, Arthur Levy of San Francisco and Walter Levy of Boston; and his two siblings.

In interviews, Dr. Levy often spoke of antibiotic stewardship — a concept that is sometimes referred to as “stuartship,” in his honor — while urging patients and doctors to avoid taking the drugs for minor ailments.

“Bacteria have seen dinosaurs come and they’ve seen them go,” he told Rather in 2011. “So we aren’t going to destroy the bacterial world. We live in the bacterial world.”