Life-threatening conditions

Pyelonephritis is an ascending urinary tract infection that has reached the pyelum (pelvis) of the kidney (nephros in Greek). If the infection is severe, the term "urosepsis" is used interchangeably (sepsis being a systemic inflammatory response syndrome due to infection). It requires antibiotics as therapy, and treatment of any underlying causes to prevent recurrence. It is a form of nephritis. It can also be called pyelitis. It presents with dysuria (painful voiding of urine), abdominal pain (radiating to the back on the affected side) and tenderness of the bladder area and the side of the involved kidney ("renal angle tenderness").

In many cases there are systemic symptoms in the form of fever, rigors (violent shivering while the temperature rises), headache and vomiting. In severe cases, delirium may be present. The presence of nitrite and leukocytes (white blood cells) on a urine dipstick test in patients with typical symptoms are sufficient for the diagnosis of pyelonephritis, and are an indication for empirical treatment. Formal diagnosis is with culture of the urine; blood cultures may be needed if the source of the infection is initially doubtful.

If a kidney stone is suspected (e.g. on the basis of characteristic colicky pain, disproportionate amount of blood in the urine), X-rays of the kidneys, ureters and bladder (KUB) may assist in identifying radioopaque stones. In patients with recurrent ascending urinary tract infections, it may be necessary to exclude an anatomical abnormality, such as vesicoureteral reflux (urine from the bladder flowing back into the ureter) or polycystic kidney disease. Investigations that are commonly used in this setting are ultrasound of the kidneys or voiding cystourethrography. Most cases of "community-acquired" pyelonephritis are due to bowel organisms that enter the urinary tract.

Common organisms are E. coli (70-80%) and Enterococcus faecalis. Hospital-acquired infections may be due to coliforms and enterococci, as well as other organisms uncommon in the community (e.g. Klebsiella spp., Pseudomonas aeruginosa). Most cases of pyelonephritis start off as lower urinary tract infections, mainly cystitis and prostatitis. Risk is increased in the following situations: Mechanical: any structural abnormalities to the kidneys and the urinary tract, calculi (kidney stones), urinary tract catheterisation, urinary tract stents or drainage procedures (e.g. nephrostomy), pregnancy, neuropathic bladder (e.g. due to spinal cord damage, spina bifida or multiple sclerosis) and prostate disease (e.g. benign prostatic hyperplasia) in men Constitutional: diabetes mellitus, immunocompromised states Behavioural: change in sexual partner within the last year, spermicide use Positive family history (close family members with frequent urinary tract infections)