The role of quorum sensing in Escherichia coli (ETEC) virulence factors

- Quorum sensing (QS) modulates virulent factor on enterotoxigenic E. coli (ETEC).
- Conditioned media (CM) increase growth, motility, F4 and LT expression on ETEC.
- CM and epinephrine on ETEC culture increase growth, motility, F4 and LT expression.
- Auto-inducer and host molecules might play important role in the pathogenesis of the ETEC.

Quorum sensing (QS) is a signaling system among bacteria mediated by auto-inducer substances (AI). Whenever the concentration of these molecules reaches a threshold corresponding to a high cell density or quorum, the whole population starts a coordinated expression of specific genes. Studies have shown that epinephrine is also responsible for activating specific bacterial genes. This work aimed to investigate the role of conditioned medium (containing AI), epinephrine and their association on growth, motility, F4 fimbriae and heat-labile toxin (LT) expression on enterotoxigenic Escherichia coli (ETEC, E68). A significant increase in motility, F4 and LT expression, was observed in the ETEC culture supplemented with conditioned medium and epinephrine. These findings suggest that ETEC uses some components of conditioned medium (e.g., AI molecules), host molecules (epinephrine), and their association to modulate the expression of important virulence genes.