They produce a chemical signal in the blood and when it reaches a threshold they all start producing toxin at once, before they can be identified by the immune system as a pathogen. It’s why the bacteria is so deadly. By the time you’re fully symptomatic it’s often too late for IV antibiotics to kill them in time.

They’re studying whether they can trick the bacteria to switch on sooner or block the receptors to keep them from quorum sensing.

Quorum sensing