Swarming motility was first reported by Jorgen Henrichsen[2] and has been mostly studied in genus Serratia,[3][4] Salmonella,[5] Aeromonas,[6] Bacillus,[7] Yersinia,[8] Pseudomonas,[9][10][11][12][13] Proteus,[14] Vibrio[15][16] and Escherichia.
[17][18] This multicellular behavior has been mostly observed in controlled laboratory conditions and relies on two critical elements: 1) the nutrient composition and 2) viscosity of culture medium (i.e. % agar).
[5] One particular feature of this type of motility is the formation of dendritic fractal-like patterns formed by migrating swarms moving away from an initial location.
Cells localized at migration front are typically hyperelongated, hyperflagellated and grouped in multicellular raft structures.
However, it has been observed that active swarming bacteria of Salmonella typhimurium shows an elevated resistance to certain antibiotics compared to undifferentiated cells.