Every infection is caused by a specific strain of bacteria. Some
antibiotics are going to work better on different strains
of bacteria. Bactrim IS used for UTI's and if it has worked before, why would your doctor not prescribe it? But again, if you are pregnant, it is pregnancy category C.
Okay, wait, I see you are 52. We are not talking pregnancy here, right? By all means, you shouldn't have to take Macrobid if you don't feel it is a good choice for you.