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Pyelonephritis is a bacterial infection that affects the kidneys: we speak of tubulointerstitial nephritis. Generally, the infection initially affects urine and bacteria reaches the renal cavities after passing through the urinary tract. Different bacterial organisms may be involved, the most common being Escherichia coli in nearly nine out of ten cases. Depending on the case, i.e. the characteristics of the person affected, a simple pyelonephritis is typically defined as occurring in women in the absence of pathology. It is called "complicated" when it occurs in a man, usually in old age or in the case of obstacles blocking the evacuation of urine, a malformation of the urinary tract, or if the person is suffering from certain diseases such as diabetes or a decrease in immune defenses.


Pyelonephritis causes the following symptoms:
  • fever;
  • chills;
  • lateralized pain in the lower back;
  • abdominal pain sometimes;
  • Fatigue;
  • Urinary disorders such as burning during urination, more frequent urination, or foul-smelling urine.

Sometimes, anuria, a stopping of the output of urine: in this case, obstructive pyelonephritis is suspected and proper treatment should be sought.


The diagnosis of pyelonephritis is based on clinical signs. The suspicion is reinforced by the completion of a urinalysis using a dipstick soaked in urine. If the reactive part, which detects white blood cells, is positive, there is a urinary tract infection. If the test is positive for nitrite, it indicates the presence of bacteria. If one of these elements present a Cyto-Bacteriological Examination is performed to confirm the presence of germs. The implementation of treatment will begin before the test results. In addition, an ultrasound of the urinary tract is required in the case of a first episode of pyelonephritis, in order to look for any possible obstacles.


The treatment of simple pyelonephritis is with antibiotics and analgesics if there is severe pain. Plenty of rest and lots of water is essential. In the case of complicated pyelonephritis, hospitalization is usually required. For obstructive pyelonephritis, care in the operating room is mandatory.


The main preventive measure of pyelonephritis, like for all urinary tract infections, is drinking lots of water.