Ethanolamine: a signal to commence a host-associated lifestyle?

Ethanolamine (EA) is a compound prevalent in the gastrointestinal (GI) environment. The ability to catabolize this compound has been associated with important GI pathogens, including enterohemorrhagic Escherichia coli O157:H7 (EHEC). It has been hypothesized that the ability of EHEC to utilize EA as a source of nitrogen provides EHEC with an important competitive advantage in the gut. However, new work by Kendall et al. (mBio 3:e00050-12, 2012) suggests that the role of EA in EHEC pathogenesis may be more fundamental; EA appears to be a signal for EHEC to commence its virulence program. In this commentary, I review the previously described connections of EA to bacterial pathogenesis in the GI tract, highlight the important findings of this new study, and note areas where further research is needed to fully comprehend the connection of EA utilization to bacterial pathogenesis.