Will this antibiotic work for my UTI even though I was already on it once and it didn't work? I am 9 weeks pregnant and I have a uti. I was put on nitrofurantoin mono/mac 100mg twice a day for 7 days. I felt better for a few days, but the infection return

Be . Be confident that your doctor is doing the right thing. The urine culture that was done shows which antibiotics will work and which will not against the bacteria that is causing the infection. If you were put on Nitrofurantoin again then I am sure the culture showed that the bacteria was sensitive to it. Recurrent uti's are very common in pregnancy, and the fact that you took the antibiotic before does not mean it will not work this time. If you need more reassurance or explanation don't hesitate to contact your doctor. Take care.