Hi "Peach", I am curious....did you have a UTI/kidney infection that did NOT show up in culture (no bacteria)? I have been going through gross hematuria with blood closts and what was kidney pain for a long time but never showed up in culture. I talked my NP into prescribing antibiotics and finally the 3rd one (cephalexan) has seemed to work, although 10 days after finishing it had a little visible blood in urine the morning I saw my urologist so he said it was not an infection. I did ask him for antibiotic and he prescribed a prophylactic nitrofurontoin mono 100 mg to take at night. Since my visit to him and starting April 2 my urine is back to normal. He wants to do a repeat cystoscopy and scheduling a CT urogram (after having a CT scan without contrast and ultrasound 4 months ago which all came back "normal" as did his first cystoscopy). I still think it was an infection that did not culture, but subsequent antibiotics have cleared up?