Several comments: 1) recently we are becoming aware that not all bacteria in urine have to be treated... and if no symptoms of a UTI, perhaps it would be best to leave well enough alone. This is the thinking in people, too, now. It is hard after nearly 30 years of treating all bacterial urine to just ignore them now, but I understand the reasoning. A strong smell is NOT a reason to treat a urinary bacteria... there should be some symptoms, too... such as frequent urination, blood in the urine, painful urination, a lot of white blood cells in the urine, presence of stones etc.
Treating the presence of bacteria in the urine can sometimes lead to the development of a 'super bug', which can be VERY difficult to get rid of it causing a problem. However, problem bacteria in urine can take many months to get rid of (in vet school, 3 months of antibiotics for a difficult urinary tract infection was not uncommon... though things have changed somewhat since then).
Did your vet tell you what bacteria was in the urine? if Enterococcus, probably not worth treating as that genus rarely causes any harm in the bladder. I have been treating problematic Enterococcus bacterial 'infections' for years, only now to discover I probably should have left them alone.
2) yeast is very unlikely to be found in urine, though I have seen it once in a diabetic cat (died soon after).
3) the presence of crystals in the urine is only an indication of what a stone might be made of (if present) and the pH of the urine. Crystals in urine are usually otherwise not of a big concern. They, in themselves, cause no harm.