tss and old tampons

What are the chances of getting toxic shock syndrome? Can you get it easily? I'm worried that I may keep a tampon in too long so I'm wondering if anyone has left thier tampon in too long. Is there any way to be safe when using tampons? Please help me! 
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Also if you use old tampons( not used ones) is that bad? 
I've had some tampons that are opened but I've never used them but I haven't touched the upper part where the tampon comes out. I have touched the lower part where the braid is and I want to use them but I'm not sure if it's safe. Can you guys please help me💚