If a person is infected with three types of bacteria at the same time, can the bacteria become "vampires"?

Author: Duan Yuechu and Huang Xianghong

In the April 18, 2024 issue of China News, a major discovery published by a research team led by Washington State University in the latest issue of eLife magazine was reported. The study pointed out that three types of bacteria, namely Salmonella enterica, Escherichia coli and Citrobacter koseri, will exhibit a special behavior after entering the human body, which can be figuratively called the "vampire" phenomenon.

These bacteria are extremely sensitive to "serine" in human blood, and even regard it as an important source of nutrition for themselves. "Serine" is an amino acid in human blood and a common ingredient in protein drinks. It is not only important to humans, but also necessary for bacteria to maintain life and growth. When these three bacteria invade the human body, they can quickly and accurately find the location of "serine", thereby competing with humans for nutrition. The researchers therefore figuratively named these bacteria "bacterial vampires."

"Some of the most common bacteria that cause bloodstream infections can actually sense chemicals in human blood," said Arden Belink, a professor at the Washington State University College of Veterinary Medicine and the corresponding author of the research team. These bacteria are one of the main causes of death in patients with severe enteritis, because patients often experience intestinal bleeding, which can serve as a gateway for bacteria to enter the bloodstream. Shockingly, it takes less than a minute for these pathogenic bacteria to successfully find the serum.

Sienna Gran, a doctoral student at Washington State University, used a high-powered microscope to carefully observe the process of bacteria snatching serine from human blood. Further research found that Salmonella has a special protein receptor called Tsr, which allows the bacteria to sense blood and swim toward it. And "serine" is one of the important chemicals in the blood that bacteria can sense and consume.

This study is of great significance. The researchers said that this achievement may lead to innovation in the medical field and bring new hope for the treatment of patients with blood infections. By gaining a deeper understanding of the mechanism by which these bacteria detect the source of blood, we may be able to develop new drugs in the future to block their ability. These drugs will have the potential to greatly improve the quality of life and health of IBD (inflammatory bowel disease) patients at high risk of blood infections.

In this study, Tom Asaki, a mathematician at Washington State University, and Zealon Gentry-Lear, Michael Shavlik, and Michael Harms, scientists at the University of Oregon, all made important contributions. Their efforts and collaboration enabled this study of "bacterial vampires" to be carried out in depth and to achieve such valuable results. This reminds us how critical and indispensable interdisciplinary cooperation and communication are on the road of scientific exploration.

In short, this discovery of three bacteria that can turn into "vampires" reveals the complex and subtle interactions between bacteria and the human body. It not only enhances our understanding of bacterial behavior and pathogenic mechanisms, but also provides new ideas and directions for the development of future medicine. We look forward to more innovative results emerging on the basis of this research, making greater contributions to human health.