I have never gotten utis, but this past year i get them almost every other month. only symptom is strong smelling urine. culture comes back negative, but antibiotics cure the smell. what could be cause them to reoccur ?

The culture of organisms from infected urine is not 100% accurate, and the methods to preserve culture speciments as well as the possibility of anaerobic organisms which specimens are not adequately protected from oxygen exposure, can contribute to "negative" cultures. There are other causes for strong smelling urine, like dehydration, when there is no infection.

Strong smelling urine is NOT UTI. There are many causes for that. Concentrated urine and what you eat e.g asparagus, garlic and many others. Pl stop taking antibiotics and drink plenty of water and avoid excess of products which cause urine to smell. If symptoms persist see a Urologist to get a proper investigation