From Qauluq:

Re: Showerheads may spray germs at you (Sept. 14): A question about the shower head germs article. . .

“If you are get­ting a face full of wa­ter when you first turn your show­er on, that means you are probably get­ting a par­tic­u­larly high load of My­co­bac­te­rium avi­um,” said Pa­ce.

Would it help to turn the shower on, and let it run for a bit before stepping into the stream of water?