Septic shock sometimes starts with unspecific symptoms that hamper the clinical diagnosis and, therefore an appropriate treatment. When the septic shock follows a fulminating course with a fatal outcome, the etiological diagnosis has to be conducted post-mortem. Sudden unexpected deaths in children and young adults are frequently the object of medico-legal autopsies. Some sudden unexpected deaths have an infectious origin, which requires further analyses, including microbiology, to establish the cause of death. Here, the case of a fatal septic shock in a 19-month old male infant is presented. After a mild foot injury, an infection by Streptococcus pyogenes progressed to septic shock with a fatal outcome as post-mortem studies demonstrated.