Abstract
Salmonella enterica serovar Typhimurium ( S. Tm)
can colonize different intracellular niches, either actively dividing or
remaining dormant to persist. Bacterial persisters are phenotypic
variants that temporarily enter a non-replicative state. This allows
them to evade host cell defenses and antibiotics, leading to chronic
infections. We previously reported that during chronic periods,
Salmonella remains within B cells in the bone marrow and spleen.
However, the dynamics of Salmonella replication and the formation
of antibiotic tolerance in infected B cells have not been studied. Here
we show that B cells are a favorable reservoir for bacterial
persistence. In vitro and in vivo experiments identified
non-replicating, persistent Salmonella subsets in splenic B
cells. These non-replicative Salmonella are tolerant to
antibiotics (cefotaxime and ciprofloxacin), while replicative bacteria
remain susceptible. Infected mice demonstrated viable, non-replicative
Salmonella in spleen B cells, maintaining antibiotic tolerance.
Although acid intravacuolar pH and SPI-2 regulators (SsrA/SsrB) are not
necessary for Salmonella persistence in B cells, the SehA/B
toxin-antitoxin system facilitates the formation of the persistent
phenotype in Salmonella. Overall, we show that B cells are a
reservoir for non-replicating, antibiotic-tolerant Salmonella.