I'm non-circumsized and did have a minor UTI when I was 6 or so because my single mother did not know to educate me on how to properly wash my Penis. I had a quick round of anti-biotics and a little chat from a Doctor, and it's been issue-free for 25 years. So I can believe that this is not a super uncommon thing to happen in the life of an uncircumsized boy. A search for more serious problems related to foreskin isn't turning up a whole lot, although circumcision is a surgery and has risks of infection itself. Especially in parts of the world where you have religious figures with improper medical training performing Brit Milah instead of surgeons simply doing the procedure in a sterile environment. I mean, for fucks sakes, a traditional Brit Milah involves a Rabbi sucking on the foreskin before performing the incision. Super, super unsanitary and frankly fucking disgusting conceptually.