Kidney Infection

What is a Kidney Infection?

A Kidney infection is an inflammation of the kidney, usually caused by bacteria or a virus. Cystitis, or inflammation of the bladder, is a common cause of kidney infection. Kidney infections are a type of urinary tract infection (UTI). The scientific name for kidney infections is pyelonephritis.

The main functions of the urinary system and kidneys:

  • Kidneys — Your kidneys remove waste from your body and extract surplus water from your blood.
  • Urethra — Your urethra is a tube that transports urine away from your bladder and allows you to expel urine outside of your body.
  • Bladder — Your bladder holds urine.
  • Ureters —  Your ureters are thin tubes that transport urine to your bladder.

Signs and Symptoms

Kidney infection symptoms usually occur within two days of an infection. Pyelonephritis symptoms sometimes differ based on your age. For example, children under the age of 2 often display a high fever. Adults over 65 might show signs of distorted speech and confusion.

Kidney infection signs and symptoms:

  • Increased urination
  • Fever
  • Groin pain
  • Back pain
  • Abdomen pain
  • Side pain
  • Foul-smelling urine
  • Nausea
  • Cloudy urine
  • Feeling cold or chills
  • Vomiting
  • Blood in urine
  • Pus in urine
  • Painful urination

If left untreated, kidney infections can lead to sepsis and death. Sepsis is a sometimes fatal response to an infection.

Signs of sepsis include:

  • Elevated heart rate
  • Rash
  • Low blood pressure
  • Chills
  • Disorientation
  • Sweaty skin
  • Clammy skin
  • Fast breathing
  • Severe pain
  • Fever


Kidney infection causes include bacteria and viruses that enter the kidneys through the urinary tract. Escherichia coli, which is also known as E. coli, is a common bacterial cause. This bacterium is usually found in the body's intestines. However, E. coli can spread from your urethra to your bladder and kidneys.

Other potential pyelonephritis causes:

  • Urinary tract infection — A urinary tract infection can spread to the kidneys.
  • Bladder surgery — Bladder surgery can cause kidney infection by introducing bacteria into the urinary tract.
  • Kidney surgery — Kidney surgery can cause a urinary tract infection by introducing bacteria into the bladder.
  • Obstruction of urine flow — An obstruction of your urinary tract can cause a kidney infection. Obstructions might include tumors, kidney stones, or an abnormally shaped urinary tract.

Risk Factors

There are certain risk factors for developing a kidney infection. These risk factors involve gender, general health, and other medical conditions.

Immune System

Some medical conditions, such as diabetes and HIV, can make it hard for your body to fight off infections. A weak immune system may also be caused by obesity, heart disease, or respiratory problems.

Certain medications also reduce your immune system’s defense against infections.


Since women have a shorter urethra than men, the female bladder is more susceptible to bacterial infection. Once an infection has made it into the bladder, it can spread to the kidneys. These infections carry a higher risk for pregnant women.

Urinary Catheter

Urinary catheters are tubes that allow you to empty your bladder of urine. They are often used during and after surgery, or if you are confined to a bed. They can cause pyelonephritis by allowing bacteria to enter your bladder.

Nerve Damage

Nerve damage can prevent you from noticing when bladder infections progress into kidney infections. Spinal cord damage can also block some of the early signs of an infection.

Individuals with nerve or spinal cord damage are encouraged to schedule regular medical examinations to prevent any unidentified conditions from getting worse.

Urinary Tract Blockage

Another risk factor that increases the likelihood of developing a kidney infection is a blockage in the urinary tract. A blockage reduces or blocks urine flow from the bladder and makes it harder to fully empty your bladder when you urinate.

Blockages might be kidney stones, tumors, an unusual structure of your urinary tract, or an enlarged prostate gland in men.

Other Urinary Conditions

Any condition that causes even small amounts of urine to flow in the opposite direction increases the risk of kidney infection. When urine flows the opposite way, bacteria can get into your ureters and kidneys.


Your doctor will usually start a kidney infection diagnoses by reviewing your symptoms. Then your doctor will perform a urine analysis and urine culture, followed by a variety of tests to identify issues with your urinary tract, bladder, and kidneys.

Pyelonephritis diagnosis tests:

  • Urine analysis — Your doctor will check your urine for bacteria, pus, and blood.
  • Urine culture — A urine culture helps your doctor identify the bacteria in your body.
  • Imaging tests — Ultrasounds or computerized tomography (CT) scans show urinary tract blockages.
  • Digital rectal exam — Doctors perform this exam on men to check for an enlarged prostate.
  • Voiding cystourethrogram (VCUG) — This is a specialized X-ray used to identify issues in your urethra and bladder.
  • Dimercaptosuccinic acid (DMSA) scintigraphy — A type of imaging test that can show how well your kidneys are functioning. DMSA scintigraphy uses radioactive material to locate damage, infection, or other abnormalities.

Treatment & Recovery

The most common kidney infection treatment is antibiotics. Antibiotics help clear up the symptoms of kidney infection. Pyelonephritis treatment time varies depending on the severity of your condition and your response to antibiotic therapy. Typically, antibiotic treatment takes up to two weeks.

People with severe kidney infections may need supplemental antibiotics and hospitalization. For individuals with recurring kidney infections, surgery is sometimes needed to correct abnormalities in the urinary tract.

Recovery and Home Treatments

You can take several steps at home to help treat and recover from kidney infections.

At-home treatments:

  • Apply a heating pad to your back, side, or belly.
  • Rest frequently during your recovery period.
  • Drink more fluids to help rid your body of toxins and germs.
  • Sit completely on the toilet when using the bathroom. This helps you empty your bladder.
  • Avoid medications that may damage your kidneys.
  • Avoid using deodorant sprays on your genital area.
  • Urinate immediately after sex.
  • Use the bathroom as soon as you feel the need.
  • Use lubricated condoms for sex.
  • Avoid spermicide-laced condoms or diaphragms.


Untreated kidney infection can result in serious health complications. You can severely injure your kidneys, which can lead to kidney disease or failure. You might develop sepsis from a bacteria-contaminated bloodstream. Rarely, you might experience high-blood pressure or scarring in your kidneys. Pyelonephritis during pregnancy can lead to newborn babies with low birth weight.

If you or a loved one experience any of the signs and symptoms of kidney infection, please contact a urologist at Baptist Health.

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