UTI's can be caused because your cat isn't drinking enough water and eats only dry food that is high in magnesium and possibly phosphorus. Some cats are more prone to UTI's than other cats.

FUS (feline urological syndrome) can be caused because a male cat is neutered, has a diet high in dried foods (probably those with a high magnesium content), low fluid intake, obesity, and inactivity.

If your cat is prone to getting a lot of UTI's, I would start by mixing some wet food with his/her dry food and making sure that he/she is drinking enough water. You may also want to talk to your vet about putting your cat on a special prescription diet for this. There are also a few pet store brands that are supposed to help cats that are prone to UTI's. My cats are all on the prescription food called Royal Canin S/O. They eat wet food mixed with dry food. This food makes them drink more water and also urinate more often. Good luck.