Urine and uti question?

ok i know how you can get bladder infections if you wipe back to front because youre spreading e coli bacteria to the urethera but i was wondering, if i wipe from front to back, and i dont wipe ALLL the urine, or i have some leftover, could that cause a bladder infection too because ill wipe but sometimes its not ALL wipped off. completely. because i know urine is sterile so if i dont get all of it, is it ok? or if i just let it drip dry is it ok?