Loss of virulence associated with absence of flagellum in an isogenic mutant of Pseudomonas aeruginosa in the burned-mouse model.

To test the importance of flagella as a virulence factor, virulent strain Pseudomonas aeruginosa M-2 was mutagenized, and a Fla mutant was isolated. An M-2 Fla spontaneous motile revertant was isolated from M-2 Fla. The three strains were biochemically and morphologically identical. Assay of Fla in the burned-mouse model showed a severe loss of virulence. The Fla revertant was fully virulent. The importance of P. aeruginosa motility (flagella) for virulence in burns infections is indicated.