During the Civil War, Union forces set up a blockade of Confederate ports to prevent cotton exports from getting out of the South and military supplies from getting in. Facing a shortage of conventional medicines that were needed to treat high rates of infection among wounded Confederate soldiers, doctors turned to traditional plant remedies. And as Rob Dozier reports for Vice, a new study suggests that at least some of these plant medicines effectively fought off dangerous bacteria.

An astounding 620,000 soldiers died during the Civil War—most of them from non-combat related diseases, according to the American Battlefield Trust. Wounds that were not fatal could be seriously life-altering. Amputation was a common treatment, and one in 13 surviving Civil War soldiers went home with at least one missing limb. Unfortunately for these soldiers, germ theory was in its nascent stages at this time. But medical experts did understand that antiseptics were important for wound care—though they didn’t know exactly why—and iodine and bromine were sometimes used to treat infections.

Without a ready supply of these and other medicines—like quinine, which was used to treat malaria, and morphine and chloroform, which helped block pain—the Confederacy enlisted botanist and surgeon Francis Porcher to compile a book of plant remedies that were available in Southern states. Drawing on the folk knowledge of white Southerners, Native Americans and enslaved Africans, Porcher published Resources of the Southern Fields and Forests in 1863, which included descriptions of 37 plant species that could be used for fighting gangrene and other infections. Samuel Moore, the Confederate Surgeon General, subsequently used Porcher’s work to produce Standard supply table of the indigenous remedies for field service and the sick in general hospitals—a field guide on native plants to be used by battlefield physicians.

For the new study, published in Scientific Reports, a team of researchers decided to test the antiseptic properties of three plants that Porcher cited in his text: white oak and tulip poplar, both of which are hardwood trees, and a thorny shrub commonly known as devil’s walking stick. Extracts were taken from various parts of the plants—including the leaves, inner bark and branch park—and tested them on three species of bacteria that are commonly seen in wound infections.

One, Staphylococcus aureus, is considered the most dangerous of the staph bacteria and often causes skin infections. Aceinetobacter baumannii, which in recent years has been associated with troops coming back from Iraq, can infiltrate wounds, the blood, bones and lungs. And Klebsiella pneumoniae is a leading cause of hospital infections that can lead to pneumonia and other serious conditions.

The researchers found that while the plants did not kill the bacteria, they had antimicrobial effects, inhibiting the growth of all three species. The plants also interfered with S. aureus’ biofilm formation, which helps bacteria stick together and to surfaces, and makes them less sensitive to antibiotics. What’s more, devil's walking stick was shown to inhibit quorum sensing, a signalling system that makes staph bacteria more virulent, in S. aureus.

“Our findings suggest that the use of these topical therapies may have saved some limbs, and maybe even lives, during the Civil War,” says Cassandra Quave, senior study author and assistant professor at Emory’s Center for the Study of Human Health and the School of Medicine's Department of Dermatology.

These results are significant not only from a historical perspective, but also because medical experts today are dealing with a growing problem of antibiotic resistance among dangerous bacteria; all three bacteria species tested in this study, in fact, have shown multi-drug resistance, according to the study. It is thus of vital important that researchers find other ways to treat bacterial infections, and traditional plant-based medicines should not be dismissed simply because they don’t kill bacteria, Quave says.

“There are many more ways to help cure infections,” she explains, “and we need to focus on them in the era of drug-resistant bacteria.”

More research is needed to determine how plant medicines might be used for treating infections in a medical setting. “I don’t believe these would be effective as an oral medication to treat a systemic infection,” Quave tells Gizmodo’s George Dvorksy, “but they could be potentially useful in wound care—perhaps formulated as a wound rinse, hydrogel, or medicated bandage.”

Moving forward, the study authors write, it could be worthwhile to look at the other 34 plants that are listed as antiseptics in Porcher’s book. With the global spread of antibiotic-resistant strains of bacteria, the researchers add, “it is increasingly important to consider all possible sources of new, and perhaps old, treatments.”