An overwhelming majority of people who think they’re allergic to penicillin might not be, according to a study conducted by University of Maryland researchers.

Over the course of 11 months, this university’s School of Medicine, located in Baltimore, skin tested 76 subjects who thought they had a penicillin allergy, according to the study. Of the subjects, who were patients at the University of Maryland Medical Center, 96 percent tested negative for a penicillin allergy.

The study’s patients thought they were allergic to penicillin, but needed penicillin for their treatments. The researchers only tested subjects they expected to test negative for an allergy based on questions they asked individuals. Once the skin tests showed a patient wasn’t allergic to penicillin, he or she received a dose of the medicine via an IV.

When considering a possible life-threatening reaction to an allergy, it wouldn’t be wise to go around testing people on a whim, said Ann Kwong, an expert in virology from the American Chemical Society.

Prior research has proven that most people are not actually allergic to the antibiotic, said Sarah Schmalzle, a coauthor of the study and an assistant professor at the School of Medicine. She added that the purpose of this university’s study was to show that it’s possible to bring the testing procedure to hospitals and other medical locations without an allergist.

“It’s feasible for healthcare providers other than allergists to do this test in the hospital, and we can optimize [patients’] antibiotic treatment, which should improve their outcome overall,” Schmalzle said. The study period ended in July 2015, and the report was published initially this past July.

Because bacteria have developed a resistance to some antibiotics, it’s imperative to use the most effective antibiotic for the infection, Schmalzle said.

“The access to the skin testing is really critical in certain situations, in certain hospitals,” said Jacqueline Bork, who was an infectious diseases fellow at the School of Medicine during the study. “Unfortunately, many people are given the diagnosis of a penicillin allergy when, in fact, it’s actually not true, so many of these people then go on to receive sub-optimal antibiotics.”

Different variations of penicillin make up a “very broad class of antibiotics,” Schmalzle said, “so if someone says they have an allergy, it eliminates a large loss of antibiotics.”

The problem with antibiotic resistance, she said, is that when people are allergic to one type of antibiotic they must be given a different antibiotic. If the antibiotic they’re allergic to is the best one to treat the infection and they’re given a more generic antibiotic, the bacteria may develop a resistance to the antibiotic because it doesn’t fight it as well.

“Different drugs have different chemical structures, and your immune system recognizes the structures,” Kwong said. “Since all the drugs in a particular class have the same general structure, there might be a general resistance to penicillin-based drugs.”

This means that if someone is allergic to one type of penicillin, he or she is allergic to all of them because the body recognizes them as similar structures, Kwong said.

“We were able to show that offering the test would get people more cost-effective therapy, more effective therapy and narrower spectrum antibiotics,” Schmalzle said.