Do bacteria need to communicate with each other for growth?

It is usually assumed that most prokaryotes, when given appropriate nutrients, can grow and divide in the absence of other cells of the same species. However, recent studies have suggested that, for growth, prokaryotes need to communicate with each other using signalling molecules, and a variety of 'eukaryotic' hormones have been shown to stimulate bacterial growth. These observations have important implications for our understanding of bacterial pathogenicity.