Converts phosphatidylinositol 3,4,5-trisphosphate (PtdIns 3,4,5-P3) to PtdIns 3-P and prevents the transition of PtdIns 3-P to PtdIns 3,5-P2. It is one of the known effectors injected by Salmonella into the host cell and is required for invasion and for an efficient generation and maintenance of Salmonella-containing vacuole (SVC). Alteration of the phosphoinositide composition of the plasma membrane causes membrane ruffling and actin cytoskeleton rearrangements. The persistence of PtdIns 3-P diverts the SCV from the endocytic pathway resulting in enlarged vesicles, which are essential to create a favorable environment where Salmonella can replicate and avoid immune defenses of the host cell. Secreted via the type III secretion system 1 (SPI-1 TTSS). Contains the consensus sequence Cys-X(5)-Arg characteristic of Mg-independent phosphatases. Belongs to the phosphatase IpgD/SopB family.