Hyperosmotic niche adaptation and tissue polyamines underlie MRSA persistence in the kidney.

MRSA persists in the kidney's hyperosmotic inner medulla by evading immune detection and utilizing tissue polyamines, with 1.8-fold increased bacterial survival observed in this niche.

• Why it matters: Understanding tissue reservoirs that enable MRSA persistence is crucial for developing strategies to prevent chronic infections and dissemination, especially in vital organs like the kidney.
• What they did: The study used intravenous USA300 MRSA infection in mice, combined with multiplexed imaging, dual-species transcriptomics, and genetic assays to identify the inner medulla as a reservoir and explore bacterial adaptation mechanisms.
• The result: Disrupting medullary osmolality with furosemide improved immune infiltration and reduced bacterial spread, while polyamines supported MRSA survival by stabilizing membranes and enhancing purine biosynthesis, highlighting potential therapeutic targets.