Summary We recently identified a hypervirulent strain of Pseudomonas aeruginosa , differing significantly from the classical strains in that it lacks the type 3 secretion system (T3SS), a major determinant of P. aeruginosa virulence. This new strain secretes a novel toxin, called ExlA, which induces plasma membrane rupture in host cells. For this study, we collected 18 other exlA ‐positive T3SS‐negative strains, analyzed their...