I hate centipedes too. They have to have a moist environment to live so there must be one nearby. YOu can apply a dessicate like boric acid that will dry up their bodies and kill them or at least keep them out, but must also find the source. Is there a leak in or under the bathroom? Could they be coming from a moist place outside like mulch with plastic under it? I don't know what kind of place you live in. Try putting screens over the drains, but I doubt that they're living in there.
Check the crawl space if you have one for dampness. Are the gutters clean and functional? They love cool moist places. There may be some condensation from your AC return ducting.
You must do your part to defeat the centipede so that we can all live in peace. If all else fails burn the place down.
I mean are there leaves and debris in the gutters that gets wet when it rains and then stays wet? Do the gutters drain freely? If the problem just started it might have to do with all of the rain the in the midwest this year. They eat spiders and other insects so maybe there's a food source like that nearby for them. The only other thing I can think is they like your cool, moist bathroom. Is there an exhaust fan for steam? Window air conditioners can leak water, but since they aren't there that probably isn't the problem. If there are trees, piles of wood or leaves nearby that could be their hideout. I found like a nest of them in a pile of wood once and also in some mulch that had plastic under it for weed control.