Streptococcus pyogenes (group A streptococcus) is a pathogen that invades non-phagocytic host cells, and causes a variety of acute infections such as pharyngitis. Our group previously reported that intracellular S. pyogenes is effectively degraded by the host-cell autophagic machinery, and that a cholesterol-dependent cytolysin, streptolysin O (SLO), is associated with bacterial escape from endosomes in epithelial cells. However, the details of both the intracellular behavior of S. pyogenes and the process leading to its autophagic degradation remain unknown. In this study, we found that host small G protein, Rab5, was associated with the pathway of autophagosome formation and the fate of intracellular S. pyogenes. Rab5 was involved in bacterial invasion and endosome fusion. In addition,this study showed that the bacterial cytolysin SLO supported the escape of S. pyogenes into the cytoplasm from endosomes, and surprisingly, a SLO-deficient mutant of S. pyogenes was viable longer than the wild-type strain although it failed to escape the endosomes. This intracellular behavior of S.pyogenes is unique and distinct from that of other types of bacterial invaders. Our results provide a new picture of S. pyogenes infection and host-cell responses in epithelial cells.