Is largely due to going down.
Group B strep is commonly found living as a relatively harmless denizen of the gut, vagina, and the mouth. It is not motile, meaning the little devil can’t move on its own, meaning it has to be placed ON the urethra to cause a UTI, if you get what I’m saying, here. *cough*
This is one point I ain’t makin’ with a GIF, so y’all will have to use your imaginations. Put 2 and 2 together and make 4, savvy?