At a low density of bacteria, the signaling molecules (autoinducers) diffuse away from the bacteria. Sufficient quantities of these molecules are unavailable for binding to the signaling receptors on the bacterial surface and the quorum sensing genes that enable the bacteria to act as a population are not activated. The bacterium then utilizes genes that enable the bacterium to act as an indiviual organism rather than as a multicellular population. Acting as individual organisms may better enable that low density of bacteria to gain a better foothold in their new environment.

At a high density of bacteria, sufficient quantities of signaling molecules (autoinducers) are available for binding to the signaling receptors on the bacterial surface and the quorum sensing genes that enable the bacteria to act as a population become activated. The outcomes of bacteria-host interaction are often related to bacterial population density. Bacterial virulence, that is its ability to cause disease, is largely based on the bacterium's ability to produce gene products called virulence factors that enable that bacterium to colonize the host, resist body defenses, and harm the body.