That was my question. Scary.
They aren't something you routinely sterilize. They're used to force back the tongue so a breathing tube can be inserted, the scope itself isn't really that invasive. They should be cleaned well though before being put back into service after being used and it sounds like somebody didn't do that an probably contaminated the other laryngoscope blades in the box they're kept in.
Perhaps it might be a good idea now to make it something you routinely sterilise.
With all due respect, that's about as invasive as you can get.