What Is Kidney Infection? What Causes Kidney Infection?

Editor's Choice
Main Category: Urology / Nephrology
Also Included In: Infectious Diseases / Bacteria / Viruses
Article Date: 15 Mar 2010 - 0:00 PDT

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Kidney infection, also known as pyelonephritis, is a type of urinary tract infection (UTI) typically caused by E. coli bacteria. The bacteria may have spread from the bladder or the urethra to one of the kidneys, infecting it. The urethra is a tube which transports urine from the bladder outside the body.

Kidney infection, if not treated promptly, can lead to serious complications, including kidney damage and sepsis (blood poisoning). It is usually treated with antibiotics. In many cases, patients with kidney infection are hospitalized.

According to the National Health Service (NHS), UK, approximately 28 to 35 English people in every 100,000 develop a kidney infection annually. Women are more commonly affected by kidney infection, as are pregnant mothers, children under two years of age, as well as individuals over 60.

There are two types of kidney infection:

• Uncomplicated kidney infection - the patient is healthy and serious complications are highly unlikely.
• Complicated kidney infection - the patient is more likely to suffer complications, perhaps because of a pre-existing illness or condition.

According to Medilexicon's medical dictionary:

Pyelonephritis is "Inflammation of the renal parenchyma, calyces, and pelvis, particularly due to local bacterial infection."

What are the signs and symptoms of kidney infection?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor, detect. For example, pain may be a symptom while a rash may be a sign.

When someone has a kidney infection it normally develops quite fast - in a day or a few hours. The patient will typically have:

• Diarrhea
• A high temperature of 38 ºc (100.4ºf) or above
• Nausea
• Uncontrollable shivering
• Vomiting
• Back pain
• Pain in the groin
• Pain in the side
• Often symptoms are worse when the patient urinates

If there is also a corresponding bladder infection (cystitis or urethritis) the individual may experience:

• Bloody urine
• Cloudy urine
• Dysuria - pain or difficult urination. Often described as a burning or stinging sensation.
• Four smelling urine
• Frequent urination
• Inability to urinate fully
• Pain in the lower abdomen

What does the urinary tract consist of?

The urinary tract consists of:

• The kidneys - the majority of humans have two kidneys, one on either side of the abdomen. Kidneys clear toxins (poisons) from blood. Urea is the most important part of the waste products that are taken out by the kidneys. The kidneys also regulate acid concentrations, as well as maintaining water balance in the body by excreting urine. Water is mixed with urea to produce urine.
• The ureters - urine passes through the connecting tubes called ureters from the kidneys to the bladder. Each kidney has one ureter connecting it to the bladder. Most of us have two kidneys, and therefore two ureters. People with just one kidney have just one ureter.
• The bladder - a hollow organ (sac, bag) in the lower abdomen that stores urine. Known as the urinary bladder.
• The urethra - a tube that carries urine from the bladder to outside the body. In males the urethra goes down the middle of the penis to an opening at the end. In males the urethra also carries semen to outside the body. In females the urethra goes from the bladder to above the vaginal opening. The urethra in females is shorter than in males.

What are the causes of kidney infections and the risk factors associated with it?

• Weakened immune systems - some patients with weakened immune systems may have a bacterial or fungal infection on their skin which eventually gets into the bloodstream and attacks the kidneys, causing an infection there.
• The urethra - Alternatively, the pathogen (e.g bacteria) may get into the urethra and reproduce in the bladder, infecting it. The infection may then spread into the kidneys.
• Toilet hygiene - after going to the toilet and using toilet paper to wipe one's anus, there may be contact with the genitals, resulting in an infection getting through and working its way up to the kidneys. The infection could also enter via the anus - E. coli, a type of bacteria, can exist in the colon and eventually cause a kidney infection.
• Female physiology - women are more vulnerable bladder infections and ultimately kidney infections than men, because their urethra is shorter, making it easier for infections to reach parts of the urinary tract more quickly.
• Urinary catheter - a urinary catheter is a tube that is inserted into the bladder through the urethra to drain our urine. Having a urinary catheter raises the risk of developing a urinary tract infection, including kidney infection.
• Kidney stones - individuals with kidney stones have a higher risk of developing kidney infection. Kidney stones are the result of a build-up of dissolved minerals on the inner lining of the kidneys.
• Enlarged prostate - males with an enlarged prostate have a higher risk of developing kidney infections.
• Sexually active females - if sexual intercourse irritates the urethra there may be a higher risk of bacteria getting inside the urinary tract, and eventually reaching the kidneys.

How is kidney infection diagnosed?

A GP (general practitioner, primary care physician) will usually check the patient's heart rate, blood pressure, temperature, and respiratory rate in order to determine what their general state of health is. The doctor will also check for signs of dehydration.

A physical exam will be carried out, with particular emphasis on the mid and lower back to see whether there is any sensitivity, pain or tenderness. If the patient is a young woman the doctor may carry out a pelvic exam to verify whether there is any pelvic inflammatory disease (PID). If the female is of childbearing age, a pregnancy test may be recommended.

Urine test - this can determine whether there is a urinary tract infection, but not where exactly in the urinary tract (urethra, bladder or kidneys). However, a urine test that detects an infection, plus some hallmark signs, such as fever, pains (especially in the side of the body), will help the doctor reach a diagnosis.

What are the treatment options for kidney infection?

Kidney infection can either be treated at home or in a hospital; this will depend on several factors, including the severity of symptoms and the patient's general state of health.

Treatment at home consists of taking prescribed oral antibiotics. The patient should start to feel better after a few days. It is essential that the individual finishes treatment and complies with what their GP has instructed, so that the kidney infection get's cured.

Consuming plenty of fluids will help prevent fever and dehydration. Fluid intake recommendations may vary, depending on the type of infection.

The doctor may also prescribe an analgesic if there is any pain.

If the individual is treated in hospital and suffers from dehydration fluids may be administered with a drip. Most cases of hospitalization do not last more than three to seven days.

Subsequent urine and blood tests will tell the doctor how effective treatment has been.

The following types of patients are more likely to be treated in hospital for kidney infection:

• Those with diabetes
• People aged 60 or over
• Individuals who have serious difficulties urinating
• Patients with cancer, and those receiving chemotherapy or radiation therapy
• Those with sickle cell anemia
• Individuals with a history of kidney infection
• People with HIV
• Patients who are found to have a blockage in their kidneys
• Pregnant women
• Patients in severe pain
• People with severe vomiting

What are the complications of kidney infection?

• EPN (emphysematous pyelonephritis) - this is a very rare complication; however, it is potentially fatal. EPN is a severe infection in which kidney tissues are destroyed rapidly. The bacteria that cause the infection release a toxic gas that accumulates inside the kidney, causing fever, nausea, abdominal pain, vomiting and confusion.
  
  Experts are not sure what the exact cause of EPN is, however, it is linked to having badly-controlled diabetes. If left untreated the patient is at serious risk of multiple organ failure and subsequent death. Emergency surgical intervention is usually required to either remove the entire kidney, or part of it.
• Kidney abscesses - pus accumulates inside kidney tissues in small pockets (abscesses). Symptoms include blood in urine, weight loss and abdominal pain. Sometimes surgery is needed to drain out the pus.
• Sepsis (blood poisoning) - also a rare but possibly life-threatening complication. Bacteria spreads from the kidneys into the bloodstream, resulting in possible subsequent infections in any part of the body, including major organs. Symptoms include hypotension (low blood pressure), confusion, disorientation, diarrhea, weaker urine flow, clammy skin, cold skin, pale skin, and loss of consciousness. It is a medical emergency and patients are usually placed in an ICU (intensive care unit).

How can kidney infection be prevented?

Often, a kidney infection is a result of a pre-existing infection in the urinary tract. The best way to prevent a kidney infection from developing is by not having bacteria in the urethra or bladder.

• Hydration - drink plenty of fluids.
• Urination - urinate whenever you feel the urge to. Don't wait.
• Sexual intercourse - urinate after sexual intercourse. Wash the genitals before and after intercourse.
• Toilet hygiene - after defecating (passing stools) wipe the anus from front to back. This lessens the risk of spreading bacteria to the genitals.
• Fiber - eat plenty of fiber so that stools come out easily and do not irritate or cause skin lesions. Constipation increases the risk of developing a urinary tract infection.
• Cranberry - studies have found that eating cranberries (or drinking cranberry juice) regularly may protect the urinary tract from infection. Patients taking blood-thinning warfarin should not take cranberry.

Written by Sebastian Nordqvist


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