So my 4.5 month old has a uti

Is this common? Anyone else's baby get one? What steps did you take to prevent a yeast infection after antibiotics? I plan on giving her probiotics

Update: I know front to back, I am a woman however my boyfriend I'd the one to blame, I won't get into that on here though, let's just say he isn't "good at it" and I have warned him many times. I have already yelled at him a bunch, because this happened after the one time he changed her diaper after pooping when I wasn't around to check it.