[YouTube - Link]
She begins with bioluminescence, and why it only occurs after bacteria have multiplied to a critical mass/concentration. She then extends the concept to virulence in human infections (the bacteria actually control their pathogenicity).
A related concept is that multicellular creatures (humans, etc) evolved [or were created, depending on your cosmic view] using an extension of the same principle of quorum sensing that bacteria use to distinguish "self" from "other."
She closes by explaining how the principles elucidated in this talk might be used to overcome antibiotic-resistant bacteria.- via videosift