猛毒バクテリア、人間の血液に渇望(Deadly bacteria show thirst for human blood)

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2024-04-16 ワシントン州立大学(WSU)

ワシントン州立大学の研究チームによる新たな研究で、世界で最も致死的な細菌の一部が人間の血液を求めており、「細菌の吸血」と呼ばれる現象が発見されました。これらの細菌は、人間の血液中に含まれる栄養素を利用するために、血液の液体部分である血清に引き寄せられています。研究結果は、eLife誌に掲載され、血流感染の発生メカニズムを新たな視点から解明し、治療法の開発につながる可能性があります。

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血清へのタキシを介して媒介されるバクテリアの吸血鬼性 Bacterial vampirism mediated through taxis to serum

Siena J. Glenn,Zealon Gentry-Lear,Michael Shavlik,Michael J. Harms,Thomas J. Asaki,Arden Baylink
eLife  Reviewed preprint version 2:April 16, 2024 (this version)
DOI:https://doi.org/10.7554/eLife.93178.2

猛毒バクテリア、人間の血液に渇望(Deadly bacteria show thirst for human blood)

Abstract

Bacteria of the family Enterobacteriaceae are associated with gastrointestinal (GI) bleeding and bacteremia and are a leading cause of death, from sepsis, for individuals with inflammatory bowel diseases. The bacterial behaviors and mechanisms underlying why these bacteria are prone to bloodstream entry remains poorly understood. Herein, we report that clinical isolates of non-typhoidal Salmonella enterica serovars, Escherichia coli, and Citrobacter koseri are rapidly attracted toward sources of human serum. To simulate GI bleeding, we utilized a custom injection-based microfluidics device and found that femtoliter volumes of human serum are sufficient to induce the bacterial population to swim toward and aggregate at the serum source. This response is orchestrated through chemotaxis, and a major chemical cue driving chemoattraction is L-serine, an amino acid abundant in serum that is recognized through direct binding by the chemoreceptor Tsr. We report the first crystal structures of Salmonella Typhimurium Tsr in complex with L-serine and identify a conserved amino acid recognition motif for L-serine shared among Tsr orthologues. By mapping the phylogenetic distribution of this chemoreceptor we found Tsr to be widely conserved among Enterobacteriaceae and numerous World Health Organization priority pathogens associated with bloodstream infections. Lastly, we find that Enterobacteriaceae use human serum as a source of nutrients for growth and that chemotaxis and the chemoreceptor Tsr provides a competitive advantage for migration into enterohaemorrhagic lesions. We term this bacterial behavior of taxis toward serum, colonization of hemorrhagic lesions, and the consumption of serum nutrients, as “bacterial vampirism” which may relate to the proclivity of Enterobacteriaceae for bloodstream infections.

医療・健康
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