This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The human body fights staph infections by starving it of essential nutrients. Staph, it turns out, is remarkably good at changing what's on the menu.
Staphylococcus aureus—the infamous agent behind MRSA and most staph infections—needs sulfur to build proteins and other materials essential for survival. In a new Michigan State University study, published in the Journal of Bacteriology, researchers found the bacterium can adjust its diet depending on what sources remain available. Understanding how S. aureus finds the nutrients it needs to survive could eventually reveal new ways to weaken the bacterium, potentially making antibiotic-resistant infections easier to treat.
The team, overseen by Neal Hammer, associate professor in MSU's Department of Microbiology, Genetics and Immunology, found that S. aureus can adjust its inner workings in response to any one of a number of different sulfur-containing compounds—like cysteine, glutathione or thiosulfate. The research was led by Paige Kies, then a graduate student in Hammer's lab. Kies is now a researcher with the Infectious Diseases Research Laboratory at the Mayo Clinic.
"Many people think of bacteria as simple organisms, but this study shows that S. aureus can effectively 'change its diet' depending on what's available," Hammer said. "It monitors its environment, activates different genetic programs and switches between nutrient sources to keep growing." Previous research had shown that much of this sulfur-sensing behavior is controlled by a regulator protein called CymR, which acts as an on-off switch for sulfur-acquisition genes. CymR keeps the genes turned off until the bacteria's sulfur supply runs low.
In the new study, Hammer's team found that when starved of sulfur, the bacteria switch on hundreds of genes, far more than CymR controls, triggering other related metabolic pathways like iron acquisition and oxidative stress defenses that also help the bacteria survive hostile conditions. When the team compared the bacteria's response to different potential sulfur sources, one unexpectedly stood out. When S. aureus had access to thiosulfate, it triggered a cascade of changes, activating far more genes than when it had access to other sulfur sources.
This finding helped the team pin down the specific function of a transporter protein the bacteria use to grow on thiosulfate. "When staph infects people, it's basically eating us," Hammer said. "But the question is: what's on the menu?
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