Kidney infection, referred to as pyelonephritis, is an upper urinary tract infection from bacteria. Very often, it is the bacteria E. coli, which live in the bowel.

Urinary tract infection usually begins in the urethra or bladder and then comes to the kidneys. Kidney infection should not be left untreated because it can either damage the kidneys or spread to the bloodstream.

The urinary tract infections are divided into: lower (urethra, bladder, and prostate gland in men) and upper urinary infection (kidneys).

Kidney infections can be: uncomplicated (infection in most cases by E. coli bacteria, or KlebsiellaProteusPseudomonas,Enterococcus, and Staphylococcus saprophyticus), complicated (obstruction, enlarged kidney, abscess) , and long-term (chronic kidney infection that can occur due to kidney stones or structural abnormalities).



The symptoms of kidney infection are:

  • Fever
  • Pain in the back, groins or stomach
  • Frequent urination
  • Urge to urinate and pain during urination
  • Nausea and vomiting

In elderly patients and those with weak immune systems, kidney infection may show more severe symptoms, like: confusion, lethargy, rapid heart rate, low blood pressure, and dehydration.



The cause of kidney infection is bacteria, which enter the urinary tract through urethra (the tube that carries urine from the body). The bacteria may ascend in the urinary system and cause kidney infections.

Sometimes, bacteria can take another route to cause kidney infection, from the bloodstream. This is usually the case when there is artificial joint or heart valve.

In rare cases, kidney infection can be caused after kidney surgery.


Risk Factors

There are many factors that may increase the risk of infection of the kidneys and urinary tract:

  • sex – women are more susceptible due to shorter urethra than men, in premenopause, women have higher risk
  • sexual intercourse (for women, as urethra are close and bacteria can easily enter the urinary tract; this condition is sometimes known as "honeymoon cystitis")
  • use of spermicide
  • pregnancy
  • post-menopausal women
  • prostate enlargment
  • urinary catheters
  • kidney stones
  • diabetes mellitus
  • race – caucasians have four times higher risk



Complications of kidney infection may arise if the infection is left untreated. These can be:

  • permanent kidney damage
  • blood poisoning as bacteria can spread when kidneys return blood to circulation
  • low birth weight if kidney infection is present during pregnancy



Prevention of kidney infection involves:

  • drinking a lot of water, to remove bacteria from the body
  • go to the toilet whenever you feel the urge
  • empty the bladder after intercourse to clear bacteria from the urethra
  • don’t use feminine products like douchers because these can irritate the urethra
  • careful wiping, i.e. it should be from front to back in order to prevent spreading bacteria to the urethra