D-mannose is a sugar with a 5 carbon ring. It is one available in drug stores and on Amazon.com. It is not the only one. These 5 carbon simple sugars cause bacteria to stop clinging to the body so that they can be flushed out. They can be used - suggesting this as an alternative for you to properly investigate for yourself - as an alternative to antibiotics for a UTI. It is better than cranberry juice.

Kidney failure is a bad way to die. From a UTI, I think it would take several painful months to simply allow it to happen. My guess, though, unless the infection is especially severe or your immune system particularly depleted, is that you will simply have to urinate all the time and you will become dehydrated. This will lower your blood pressure until you faint somewhere in public and wake up in hospital with an IV of fluids and antibiotics.