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Date of last update: 10/09/2017.

Forum Name: Miscellaneous Nephrology Topics

Question: Blood in urine, negative culture, male

 LisaLou - Tue Jul 24, 2007 7:44 am

My teenage son awoke with low back pain and fever 4 days ago. His regular doctor said there was blood in his urine sample and would grow a culture. She perscribed Bactrim. The next day, fever was 102-103, continued low back pain, burning with urination, chills, shivering, vommiting. Also color of urine was orange. Regular doctor sent us to ER. The ER did a CT scan that ruled out kidney stones. Said that young healthy males his age do not usually get urinary tract infections, but that must be what he had according to his urine sample, although blood count was normal. ER told us to stop Bactrim and put him on Keflex instead. Also gave him nausea medicine and also phenazophyridin to help him urinate easier.
Yesterday he was even worse, so we saw a urologist. The urologist could not get a copy of his culture report, but said to continue on as we were doing and push fluids and he would improve soon. However, when I called the regular doctor back to find out about culture that was done 3 days ago, they said the culture was negative. How can the culture and bloodwork be normal? He still has high fever, chills, low back pain, blood in urine and burning when he urinates.
 Dr. Chan Lowe - Mon Jul 30, 2007 9:20 pm

User avatar Hi LisaLou,

There are a few possible reasons. One is that the bacteria that is causing the infection may be difficult to culture. This is generally unlikely. Another, very real possibility is that he has a virus causing the infection. There are several viruses that can cause urinary tract infections and will not show up on a culture. These will generally resolve in 5-7 days or so.

Also, if the urine was very dilute during the initial part of the infection there may have not been enough bacteria present to grow on culture.

If his symptoms do not resolve I would recommend he follow up with the urologist for further evaluation. Cephalexin (Keflex) is generally quite adequate for UTI's so if it is a bacteria it almost certainly will be covered by the antibiotics. If the infection is also present in his kidneys (as it sounds based on his back pain) it may take a few more days to start to feel better than it would if it were a simple UTI.

Best wishes.

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