Motility Matters: Quantitative Analysis of Salmonella Swimming and Swarming.

Salmonella motility plays an essential role in environmental survival and virulence, enabling cells to access nutrients, colonize host tissues, evade host immune responses, and persist in diverse environments. These movements, driven by peritrichous flagella, allow bacteria to swim through liquids and swarm across surfaces, making motility a valuable phenotypic indicator in microbiological characterization. This chapter describes quantitative protocols for assessing swimming and swarming motility on semisolid agar media. Procedures include media preparation, culture standardization, bacterial inoculation, incubation under defined conditions, and measurement of motility zones over time. These methods provide a reliable framework for evaluating motility phenotypes across Salmonella isolates and can be readily applied in diagnostics, research, and teaching laboratories.