Kidney Infections

A kidney infection is a serious complication of a urinary tract infection (UTI). If left untreated, it can lead to serious health problems. 

At Banner Health, we are here to help you understand kidney infections and provide effective treatments and preventive tips. 

What is a kidney infection?

A kidney infection, or pyelonephritis, happens when bacteria enter the urinary tract and travel up to one or both kidneys. It usually starts with a UTI in the bladder or urethra (the opening where urine comes out).

Without treatment, a kidney infection can cause lasting damage to the kidneys and individuals can become very ill quickly. This is why it’s dangerous when a UTI spreads to the kidneys.

What causes a kidney infection?

Most kidney infections are caused by bacteria, often E. coli (Escherichia coli). Other types of bacteria include P. mirabilis (Proteus mirabilis) and Enterobacteriaceae.

Your kidneys and urinary tract filters waste products from your bloodstream and eliminates them as urine through the bladder and urethra. Sometimes, bacteria from the skin or rectum (anus) can enter the urethra and move up into the bladder, causing a UTI (this is referred to a cystitis when localized to the bladder).

If the infection is not treated, the bacteria can continue to travel up the ureters (the tubes that connect the bladder to the kidneys) and reach the kidneys. 

Who is at risk for kidney infections?

Certain people are more likely to get kidney infections. Here are some common risk factors:

• Your anatomy: Women are at higher risk because they have a shorter urethra. This makes it easier for bacteria to reach the bladder and kidneys.
• Injury or structural problems: Spinal cord injuries or problems, such as vesicoureteral reflux (a backward flow of urine) or a misshapen urinary tract or bladder, can also increase the risk of infection.
• Pregnancy: Pregnancy changes the urinary tract and can increase the risk of infections.
• A weakened immune system: Conditions like HIV/AIDS and diabetes can weaken the immune system. Certain medicines can make it harder to fight infections.
• Older adults: Aging can affect bladder function and increase the risk of infections.
• Catheter use: A urine catheter can introduce bacteria into the urinary tract.
• A blockage: Anything that slows the flow of urine or makes it harder to empty the bladder fully can raise the risk of an infection. This includes kidney stones, uterine prolapse and an enlarged prostate.
• Certain behaviors: Being sexually active, using spermicide and diaphragms or holding in urine can increase the risk for an infection. 

What are the symptoms of a kidney infection?

Signs and symptoms can vary from person to person and may depend on age. Symptoms may include:

• Pain or tenderness in your lower back or side near your kidneys
• A high fever or chills
• Pain or burning when you urinate or void
• The need to urinate more than usual
• Cloudy or smelly urine
• Feeling sick to your stomach or throwing up
• Feeling very tired or weak

In children and older adults, symptoms might be less obvious. Some children may have a high fever or problems peeing. Some may not be able to describe their pain or discomfort clearly to you. Instead of clear pain or fever, older adults may experience confusion, weakness or changes in mental status.

See your health care provider if symptoms continue beyond a few days or if they worsen. 

What are the complications of a kidney infection?

If left untreated, a severe kidney infection can lead to dangerous complications including:

• Kidney damage
• Kidney abscess (pus collection in the kidney)
• Pregnancy problems, like preterm birth and low birth weight
• High blood pressure (hypertension)
• Blood infection (sepsis)

Sepsis is a medical emergency that requires immediate treatment. It is a full body infection caused by a large number of bacteria. Without fast medical treatment, it can lead to organ failure and even death. 

How is a kidney infection diagnosed and treated?

A kidney infection can develop quickly over a few hours or days. Any of the above symptoms should trigger a visit to your health care provider. Don’t wait. 

Your provider can diagnose a kidney infection with a physical exam and urine test (urinalysis and/or urine culture). A urine sample is analyzed for bacteria, white blood cells and other signs of infection. They may also test your blood and get images of your kidneys. 

If you test positive, your provider will treat the infection with antibiotics. These medications will clear the bacteria from your system. If you are on oral antibiotics, take them as prescribed and finish the entire prescription. 

If your kidney infection is severe, you may need hospital treatment. This could include intravenous (IV) antibiotics and fluids.

To help you feel better, you might:

• Use pain medicine: Over-the-counter (OTC) pain relievers, such as ibuprofen and acetaminophen, can help manage pain and reduce fever.
• Stay hydrated: Drinking plenty of fluids helps flush out bacteria from your urinary system and keeps you hydrated.

Ways to prevent kidney infections 

When it comes to preventing kidney infections, it’s also about preventing UTIs. Here are some ways you can help avoid an infection:

1. Drink plenty of water throughout the day.
2. Wipe from front to back after using the bathroom.
3. Don’t hold your urine. Go when you need to go.
4. Wear cotton underwear, which allows your genital area to breathe and reduces moisture buildup. 
5. Avoid using douches or scented tampons.
6. Urinate after sexual intercourse.
7. Be careful with birth control. Talk to your provider about alternatives to spermicide and diaphragms.
8. If you are postmenopausal and experience recurrent UTIs, talk to your provider about vaginal estrogen therapy.
9. Manage chronic conditions like diabetes and HIV/AIDS.
10. Keep your genital area clean and dry. Avoid using harsh soaps and deodorant sprays that can irritate the urinary tract.
11. Don’t rely on cranberry juice supplements or D-mannose. There is little evidence these show any benefit.

If you experience recurrent UTIs, your physician may refer you to a urologist who can tailor specific therapy to prevent recurrent infections. 

Getting care

If you have questions or are experiencing symptoms of a kidney infection, make an appointment with your health care provider or a Banner Health specialist. A timely diagnosis is important to getting you on the road to recovery.