 [ Symptoms ] what causes toxic shock syndrome [ Disease ] the primary cause of toxic shock syndrome is a toxin produced by the bacterium staphylococcus aureus two conditions are necessary the bacteria need an environment in which they can grow rapidly and release toxins such as a tampon saturated with blood menstrual sponge diaphragm or cervical cap that has been left in the vagina for a very long time then the toxins must have a way of getting into the bloodstream sliding a tampon into place in the vagina may make microscopic tears in its walls rupturing tiny blood vessels a superabsorbent tampon    especially if it is left in place too long or if it is used when the menstrual flow is light    can dry out the vagina making such tearing even more likely