Difference between Urinary Tract Infection and Kidney Infection
By Theydiffer - September 8, 2015

The urinary system is a vital component of the body which functions primarily to eliminate fluid waste products. Thus, a disease in one of its organs can be life threatening. This article will focus on two diseases of the urinary system, namely urinary tract infection and kidney infection.


Urinary tract infection or simply UTI has different names depending on the affected organ. If the infection involves the bladder it is known as cystitis or a bladder infection. If it involves the urethra it is known as urethritis. Therefore the term urinary tract infection is a general term refering to a disease in any part of the urinary system. Symptoms felt would vary depending on the location of the infection.

Kidney infection refers to UTI affecting the kidneys: the glomeruli and/or the tubules. Symptoms include fever, pain along the sides, painful urination, and polyuria or frequent urination.

Comparison Chart

Urinary Tract InfectionKidney Infection
Affects the urinary systemAffects the kidneys
Symptoms vary depending on location of the disease; they usually include lower back pain, pain above the pubic bone, painful urination, and frequent urination.Symptoms include fever, nausea, vomiting, pain along the sides, painful urination, and polyuria or frequent urination.
Caused by Escherichia coli and other bacteria, although viruses, and fungi can also be a cause.Caused by spread of infection from other areas such as the bladder or pelvis, it can also be an autoimmune disorder.
Complications include recurrence, low birth weight and premature infants, urethral narrowing, chronic kidney problems, and sepsis.Complications include permanent kidney damage, blood poisoning, and pregnancy complications.
Treatment includes oral antibiotics and analgesics.Treatment includes intravenous antibiotics and analgesics; hospitalization is required for those with more severe infection.

Urinary Tract Infection vs Kidney Infection

What is the difference between urinary tract infection and kidney infection? Let us compare the two in terms of affected area, symptoms, causes, complications, and treatment.

  • Urinary tract infection is a general terminology pertaining to any disease affecting any organ of the urinary system. Depending on the organ affected it takes a new name; for example if the kidneys are involved, it is known as kidney Infection.
  • Since urinary tract infection involves the whole urinary system, the symptoms vary depending on the location of the disease. It usually includes lower back pain, pain above the pubic bone, painful urination, and frequent urination. The pain felt could range from mild to severe. As for kidney infection, pain could be felt along the sides accompanied by fever, nausea, and vomiting. Lower back pain, pain above the pubic bone, painful urination, and frequent urination can also be observed in kidney infection.
  • The number one cause of urinary tract infection is bacteria, particularly Escherichia coli, the cause of 80 to 85 percent of all urinary tract infections. This is followed by Staphylococcus saprophyticus which causes 5 to 10 percent. Bacteria would usually enter the urethra and if left untreated would spread towards other organs and parts of the urinary tract. Other causes of urinary tract infection include viruses, fungi, and healthcare-associated disease like catheter infection. Health-care associated diseases would include a wide range of pathogens. Kidney infection on the other hand is caused by the spread of infection from other areas such as the bladder or pelvis. It can also be an autoimmune disorder such as lupus nephritis (this is caused by systemic lupus erythematous).
  • If urinary tract infection is left untreated or inadequately treated, it can cause several complications such as the following: recurrence – there is a higher chance of recurrence for female patients due to the anatomy and close proximity of the openings of the anus, vagina, and urethra; for pregnant mothers there is a higher chance of delivering a low birth weight or a premature infant; males who have experienced recurrent UTIs can suffer urethral narrowing; chronic kidney problems can also occur in untreated UTIs; and sepsis can set in if the infection persists.
    As mentioned above, kidney infection is a result of a complication in UTIs. Thus, if left untreated it can then cause permanent kidney damage affecting the whole body. The kidney functions to filter waste from the blood. If the kidneys are damaged, it cannot properly filter blood, thus blood circulating in the system will contain bacteria causing blood poisoning or septicemia. And just like with UTIs, pregnant mothers may deliver a low birth weight infant.
  • Treatment of urinary tract infection includes antibiotics to control the spread of infection and analgesics to control pain. The duration of taking antibiotics will depend on the severity of the infection. It could be as short as three days or as long as a week. The important thing to remember when taking oral antibiotics is to consume the total required dosage to prevent re-infection. For kidney infection, antibiotics and analgesics are also given. But in severe cases hospitalization with intravenous antibiotics is a must. The duration of treatment and confinement will depend on the severity.