American Civil War plant medicines inhibit growth, biofilm formation, and quorum sensing by multidrug-resistant bacteria

Micah Dettweiler,Ryan M Reddinger,Cassandra L Quave,Daniel V Zurawski,James T Lyles,Brandon Dale,Kate Nelson

doi:10.1038/s41598-019-44242-y

Micah Dettweiler, Ryan M Reddinger + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-44242-y

Copy DOI

Abstract

A shortage of conventional medicine during the American Civil War (1861–1865) spurred Confederate physicians to use preparations of native plants as medicines. In 1863, botanist Francis Porcher compiled a book of medicinal plants native to the southern United States, including plants used in Native American traditional medicine. In this study, we consulted Porcher’s book and collected samples from three species that were indicated for the formulation of antiseptics: Liriodendron tulipifera, Aralia spinosa, and Quercus alba. Extracts of these species were tested for the ability to inhibit growth in three species of multidrug-resistant pathogenic bacteria associated with wound infections: Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii. Extracts were also tested for biofilm and quorum sensing inhibition against S. aureus. Q. alba extracts inhibited growth in all three species of bacteria (IC50 64, 32, and 32 µg/mL, respectively), and inhibited biofilm formation (IC50 1 µg/mL) in S. aureus. L. tulipifera extracts inhibited biofilm formation (IC50 32 µg/mL) in S. aureus. A. spinosa extracts inhibited biofilm formation (IC50 2 µg/mL) and quorum sensing (IC50 8 µg/mL) in S. aureus. These results support that this selection of plants exhibited some antiseptic properties in the prevention and management of wound infections during the conflict.

Highlights

Antibiotic resistance in pathogenic microbes poses a significant threat to human health[1]; antibiotics are critical in treating bacterial diseases and in enabling surgery and other procedures with high risks of infection
Commensal members of the microbiome may compete with pathogenic bacteria or may themselves become pathogenic under certain circumstances
The natural product compositions investigated in this study are plant extracts used during the American Civil War (1861–1865), a period of history in which infections were treated without the use of modern antibiotics and before the emergence of germ theory

Summary

Introduction

Antibiotic resistance in pathogenic microbes poses a significant threat to human health[1]; antibiotics are critical in treating bacterial diseases and in enabling surgery and other procedures with high risks of infection. The natural product compositions investigated in this study are plant extracts used during the American Civil War (1861–1865), a period of history in which infections were treated without the use of modern antibiotics and before the emergence of germ theory. While soldiers certainly used onions in their cooking, we know that antimicrobial agents such as ajoene and allicin found in garlic and onions have an impact on quorum sensing and biofilm to disrupt infections[6,7]. At the time, they were used to treat powder burns. Plants in particular produce a large variety of secondary metabolites to interact with their environments, and some of these serve to control local microbes by encouraging or inhibiting bacterial growth and/or function

Objectives

Methods

Results

Conclusion