When Roi Gazit started studying how long-term illness affects the body, he expected to find lasting damage. What he found was something unexpected: a complete recovery. Researchers at Ben-Gurion University of the Negev in Israel have discovered that while chronic Salmonella infections seriously harm blood stem cells, these same cells bounce back fully once the infection is cleared with antibiotics. The study, published in the journal Cell Reports, offers good news for anyone concerned about long-term bacterial infections and hints at a simple rule that could make bone marrow transplants safer.
Blood stem cells live deep inside your bones, in a squishy tissue called bone marrow. Think of them as tiny factory workers that never sleep, constantly making all the blood and immune cells your body needs. In a healthy person, more than 90 percent of these cells stay in a quiet, dormant state — basically taking a nap. This nap isn't laziness; it protects them from wear and tear, keeping them strong for when they're really needed.
The research team, led by Prof. Roi Gazit and Dr. Ofir Cohen from BGU's Shraga Segal Department of Microbiology, Immunology and Genetics, used a long-term lab model to see what happens when Salmonella, a bacteria that can cause lasting gut infections, stays in the body for weeks. After just 14 days of infection, the damage was striking. The stem cells lost almost all their ability to do their job. When researchers tried transplanting these "sick" cells into healthy hosts, they couldn't rebuild a blood system at all. The infected mice also showed clear signs of full-body stress: weight loss and spleens that swelled to enormous sizes as their bodies fought the bacteria.
Looking closely at what went wrong inside the bone marrow, the team used powerful genetic tools to examine each stem cell one by one. They found that the infection was forcing the dormant cells awake all at once. These exhausted cells were pushed into a constant cycle of dividing and duplicating, burning themselves out. Instead of producing a balanced mix of blood cells, they pumped out only inflammatory white blood cells, throwing the whole system out of whack. The cells' own genes became flooded with alarm signals linked to severe stress and inflammation.
Here is where the story turns hopeful. When researchers gave the infected mice a full course of antibiotics that cleared the Salmonella, everything started healing — fast. Weight returned to normal. The swollen spleens shrank back to their proper size. Inside the bone marrow, the genetic mayhem disappeared. The hyperactive, burned-out stem cells finally calmed down and retreated back into their protective dormant state. Most remarkably, lab tests confirmed that these recovered stem cells worked just as well as cells that had never been infected at all. They fully regained their ability to rebuild healthy blood and immune systems.
The researchers say this discovery comes with a practical takeaway for medicine. When someone donates bone marrow for a transplant, doctors should make sure the donor's infection is fully treated first — and give the stem cells time to rest before using them. "Cure the donor's infection and let the stem cells rest before trying to transplant them," they wrote. "By proving that adult stem cells can fully bounce back even after a severe, long-term bacterial challenge, this research highlights how critical it is to check a donor's immune health to guarantee a successful transplant."