I am no vet...but I have had cats for many years. I do not feed them inexpensive dry food. I feed them canned foods. There seems to be something associated with dry food that leaves them more prone to UTI's... not sure what it is.
I also give my cat a teaspoon of Cod Liver Oil once a month for hair balls that build in the digestive tract. They seem to like it so it is quite easy to get them to take it - and it does the trick!