Acute pyelonephritis is a suppurative inflammation of the renal parenchyma and the renal pelvis. It is a potentially life threatening condition caused by bacterial infection. It can occur suddenly and causes the kidneys to swell, which may damage them permanently too. If the condition occurs repeatedly, it is termed as chronic pyelonephritis.
The most common bacteria involved in causing pyelonephritis is Escherichia coli. Other causative bacteria are Klebsiella and Pseudomonas. Infection starts in the lower urinary tract as a urinary tract infection. Urethra provides an entry for the bacteria, which enter the tract and begin to multiply and spread up to the bladder. They further travel through the ureters to the kidneys. Any septic infection in the bloodstream can also spread to the kidneys and cause acute pyelonephritis.
How it spreads - Pyelonephritis spreads through two routes, homogenous or from the lower ascending tract (ascending infection).
Risk factors - Urinary obstruction, vesicoureteral reflex, catheterization, pregnancy, Diabetes Mellitus, age over 65.
Symptoms - The symptoms are observed within two days of infection. Common symptoms include:
The symptoms observed can vary in children and older adults than they are in other people. Mental confusion is common in older adults and it often is their only symptom. In chronic pyelonephritis, people experience only mild symptoms or may even lack noticeable symptoms altogether, which is the major reason of negligence by the patient towards treatment. Flank pain in the abdomen and signs of infection can be observed.
Diagnosis - Uncentrifused urine is analyzed for the presence of pus cells. The leucocyte esterase dipstick method is used to check for Pyuria. However, it is less sensitive than microscopy. In the urine culture, significant bacteriuria is detected on presence of more than 105 colonies/ml of the sample. Imaging studies can be done to check for the presence of kidney stones. Amongst the inflammatory markers, the values of C-reactive protein (CRP), ESR, and plasma viscosity may be raised. An elevated white cell count with neutrophilia is seen on blood culture.
Complications - Abscess formation in either the kidney parenchyma or the surrounding retroperitoneal spaces is a common complication. Other complications include the development of a xantho-granulomatous or emphysematous pyelonephritis. In severe cases, there can be chronic renal failure too.
Treatment - The duration of treatment depends on spread of infection. Empirical antibiotic treatment can be started until the confirmatory tests reports of culture and sensitivity are observed. Antibiotics like Ciprofloxacin, Amoxicillin, Cefixime can be given. Medications for acute pyelonephritis are continued for up to 3 weeks, whereas for chronic conditions medicines should be given for 6 months.
Chronic pyelonephritis - It is a morphologic entity which is associated with a predominant interstitial inflammation and scarring of the renal parenchyma. There is a grossly visible scarring and deformation of the pelvic-calyceal system. Chronic pyelonephritis further leads to chronic renal failure.
The two forms of chronic pyelo-nephritis are
Management includes controlling blood pressure to slow the progression of chronic kidney disease, long term antibiotic coverage for urinary tract infection, removal of calculi and antibiotic prophylaxis for vesico-ureteral reflex.