What is kidney infection (pyelonephritis)?

Kidney infection (pyelonephritis) is a bacterial infection. The disease occurs in roughly 3 to 7 of every 10,000 people in the United States. It is readily treatable if diagnosed early.

A bacteria called Escherichia Coli (E Coli) causes about 90% of kidney infections. The bacteria migrate from the genitals through the urethra into the bladder and up the tubes (ureters) that connect the bladder to the kidneys.

Normally such bacteria are flushed out by the flow of urine. However, if the urine flow is obstructed by structural abnormalities, kidney, an enlarged prostate gland (benign prostatic hyperplasia) compressing the urethra, or backflow (reflux) of urine from the bladder to the kidneys, the bacteria can gain a foothold. Some bacteria such as staphylococcus infections can enter the kidneys from the bloodstream.

What are the causes of kidney infections (pyelonephritis)?

People with urinary tract abnormalities, kidney stones, benign prostatic hyperplasia (enlarged prostate), or reflux are at risk of developing kidney infections. Those with diabetes and immune systems weakened by disease or therapeutic interventions for disease are also at risk. Pregnant women are at risk because the enlarging uterus can squeeze the ureters and reduce the flow of urine allowing the bacteria to migrate to the kidneys.

What are the symptoms of kidney infection?

A number of symptoms can indicate to your doctor that you may have a kidney infection. Symptoms of a kidney infection include:

  • Sudden onset of chills
  • Fever
  • Pain in the lower back or side
  • Nausea
  • Vomiting
  • Abdominal muscles may contract

More general symptoms of kidney infection includes:

  • Flushed or reddened skin
  • Painful urination
  • Increased urination
  • Unproductive attempts to urinate despite feelings of urgency
  • General ill feelings
  • Cloudy urine
  • Abnormally colored urine
  • Blood in the urine
  • Foul smelling urine

If you experience any of these sudden onset symptoms, please seek medical attention.

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