Bacteria experience a broad range of environmental conditions including dynamic fluid flow that affects surface colonization. It has been assumed that high shear rates would reduce colonization; however, during infective endocarditis, bacteria colonize heart valves, which is a niche with high flow speed. Gitai and colleagues explored this counterintuitive colonization behaviour using a microfluidic system. They focused on methicillin-resistant Staphylococcus aureus and Enterococcus faecalis, which are bacterial species that have been implicated in endocarditis infections. Surface colonization of the bacteria was greater in high shear conditions, whereas other species such as Escherichia coli and Streptococcus pneumoniae did not exhibit increased colonization in high flow. The authors found that S. aureus cell clusters produce a quorum system dispersal signal, and high flow increases the transport of this signal, whereas low flow leads to its accumulation, the downregulation of adhesins and hence cell detachment. By contrast, the formation of linear cellular chains promotes flow-dependent surface attachment of E. faecalis and less dispersal in the presence of higher shear force. In sum, these two mechanisms enable bacteria to colonize surfaces under high flow speeds, which could be a competitive advantage.