Answer:
Salmonella are made of Flagella which prevent it from being phagocytosed.
Flagella is a long filamentous organelle responsible for bacterial motility. falgella are present exteranlly in all three dimensionally in salmonella and it helps salmonella to swim in liquid conditions and rotates the flagella on firm surfaces.
Flagella is known as PAMPs (pathogenic molecular patterns) in salmonella which is used by the host to identify bacteria and activate the immune system of the bacteria.
Hence, rotating or motility and immune function of flagella in salmonella prevent it from being phagocytosed.