WASHINGTON – Monroe Romansky, an infectious-disease doctor who in the 1940s developed a beeswax-and-peanut oil formula that prolonged the duration of penicillin in the body, died Saturday at Sibley Memorial Hospital of complications from Alzheimer’s disease. He was 95.

Romansky’s Formula, as his discovery came to be known, transformed the treatment of wartime infectious diseases such as syphilis and pneumonia.

“To keep penicillin in the body longer, scientists have tried out a dozen different methods,” a 1946 Newsweek article reported. “One of the best is penicillin mixed with beeswax and peanut oil, discovered by Dr. Monroe J. Romansky.”

He was working at Walter Reed Army Medical Center during World War II, when physicians were searching for ways to fight numerous battlefield diseases and infections. The most valuable antibiotic then was penicillin, discovered in 1928 by Alexander Fleming and mass-produced during World War II. But penicillin was a short-acting drug that required injections every three hours.

Romansky’s technique involved substituting his wax-and-oil mixture for the saline water solution generally used in administering penicillin. He developed an eight-day treatment for syphilis that required a single injection a day.

President Harry S. Truman awarded him the Legion of Merit for his contribution, which was credited with saving thousands of lives and reducing suffering.

Romansky was a humble man who never talked about himself, said his son, Stephen Romansky of Lexington, Mass. “He always felt that he had made a contribution to the people on the battlefield,” his son said. “He worked three or four years on [the formula]. I think he was proud of it, but it was not hubris.”

By the time Romansky’s method was supplanted by semisynthetic penicillin in the 1950s, he was teaching at George Washington University. His subsequent research led to the development of many antibiotics, including streptomycin and cephalosporins. In 1949, he wrote the first report of another “wonder drug,” Chloromycetin, which could be used in the treatment of early syphilis.

Romansky, who wrote more than 150 articles, monographs and books, became a professor of medicine at George Washington University Medical School in 1947. He later was chief of infectious diseases at D.C. General Hospital and at GW’s medical school. He also had a private practice from 1970 until retiring in 1991.

Romansky was born March 13, 1911, in Hartford, Conn. He had a brother who died in the flu epidemic of 1918. He graduated from the University of Maine in 1933, excelling academically and athletically. Known as Mun Romansky, he played baseball, football and basketball and was all-New England in the three sports and an all-American honorable mention in football.

While attending medical school at the University of Rochester, he supported himself by pitching semipro baseball. There he did his residency, conducted kidney research and, after graduating in 1937, stayed on as a fellow in infectious diseases.

During World War II, he was serving in the Army Medical Corps at Walter Reed when he made his discovery.

In the late 1940s through the 1960s at GW’s medical school, where he helped train a generation of physicians, he was known as a charismatic teacher. During this period, he also ran a venereal disease clinic at D.C. General.

He also was a much-sought-after infectious disease consultant and diagnostician in the Washington area, both to other doctors and patients with complex medical problems.

Once he was surprised by a patient he was asked to treat.

“He was urgently called by a staff member of President Franklin Roosevelt to evaluate a member of his family,” Stephen Romansky recalled. “A limousine arrived at Walter Reed and my father opened the door, and to his surprise there sat Fala, President Roosevelt’s dog, who was sick and required an injection of penicillin.”

Besides his son, survivors include his wife of 63 years, Evelyn Romansky of Chevy Chase, Md.; three other sons, Jerry Romansky of Washington, Michael Romansky of Chevy Chase and Richard Romansky of Herndon, Va.; and 11 grandchildren.