Superbugs Are Losing to Science, Light, and a Little Spice

Texas A&M researchers have found that curcumin, when activated by light, can weaken antibiotic-resistant bacteria, restoring the effectiveness of conventional antibiotics.

Curcumin: A Surprising Ally Against Superbugs

In 2017, a woman admitted to a Nevada hospital with pneumonia died from multiple organ failure and sepsis. The cause? A strain of bacteria resistant to 26 different antibiotics. These antibiotic-resistant bacteria, known as superbugs, pose a serious and growing global health threat.

In the fight against these dangerous pathogens, researchers at Texas A&M have discovered a potential new tool—curcumin, the natural compound that gives turmeric its bright yellow color.

Their study found that when bacteria consume curcumin and are then exposed to light, harmful reactions occur within the microbes, ultimately killing them. This approach reduces the number of antibiotic-resistant strains and restores the effectiveness of conventional antibiotics.

The findings were published in Scientific Reports.

The Antibiotic Crisis and the Rise of Superbugs

Before antibiotics, infectious diseases were the leading cause of death and disability around the world. With the advent of these life-saving medications, the human lifespan has increased by 23 years on average. In the last several decades, while the discovery of novel antibiotics has plateaued, antibiotic-resistant bacteria have simultaneously become more common, ushering in the era of superbugs, such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus, and pneumonia, which are all extremely hard to treat. In fact, infectious diseases are projected to be the main causes of human mortality once again, claiming up to 10 million lives annually.

A New Strategy to Overcome Antibiotic Failure

"When bacteria start becoming resistant to conventional antibiotics, we have what we call an antibiotic catastrophe," said Dr. Vanderlei Bagnato, professor in the Department of Biomedical Engineering and senior author on the study. "To overcome this challenge, we need alternative ways to either kill the superbugs or find a novel way to modify natural processes within the bacteria so that antibiotics start to act again."

Bacteria display natural variation within a given population. This heterogeneity introduces variations in cell behaviors, including response to antibiotics, which can directly contribute to treatment resistance if some strains survive antimicrobial medication and continue replicating. Thus, the researchers wanted to curb bacterial heterogeneity to control bacterial resistance.

Harnessing Light to Kill Drug-Resistant Bacteria

Photodynamic inactivation, a technique that has shown promise in combating bacterial resistance, uses light and light-sensitive molecules, called photosensitizers, to produce reactive oxygen species that can kill microorganisms by disrupting their metabolic processes. In their experiments, the team used curcumin, which is also a natural food for bacteria. They tested this technique on strains of Staphylococcus aureus that are resistant to amoxicillin, erythromycin, and gentamicin.

A Game-Changer for Antibiotic Effectiveness

The researchers exposed the bacteria to many cycles of light exposure and then compared the minimum concentration of antibiotics needed to kill the bacteria after light exposure versus those that did not get light exposure.

"When we have a mixed population of bacteria where some are resistant, we can use photodynamic inactivation to narrow the bacterial distribution, leaving behind strains that are more or less similar in their response to antibiotics," said Bagnato. "It's much easier now to predict the precise antibiotic dose needed to remove the infection."

Expanding the Potential of Curcumin Therapy

The team noted that photodynamic inactivation using curcumin has tremendous potential as an adjuvant or additional therapy with antibiotics for diseases, like pneumonia, caused by antibiotic-resistant bacteria.

"Photodynamic inactivation offers a cost-effective treatment option, which is crucial for reducing medical expenses not only in developing countries but also in the United States," said Dr. Vladislav Yakovlev, professor in the Department of Biomedical Engineering and author on the study. "It also has potential applications in military medicine, where this technology could be used to treat battlefield wounds and prevent the development and spread of antimicrobial resistance, a significant concern in combat situations."

Reference: "Photodynamic inactivation and its effects on the heterogeneity of bacterial resistance" by Jennifer M. Soares, Vladislav V. Yakovlev, Kate C. Blanco and Vanderlei S. Bagnato, 16 November 2024, Scientific Reports.
DOI: 10.1038/s41598-024-79743-y

Contributors to the research include Dr. Jennifer Soares, who is the primary author on the paper, and Dr. Kate Blanco from the Institute of Physics of São Carlos, University of São Paulo, Brazil.

This research was financially supported by the São Paulo Research Foundation, the National Council for Scientific and Technological Development, the Cancer Prevention and Research Institute of Texas, the Governor's University Research Initiative, the Air Force Office of Scientific Research, and the National Institutes of Health.