What Is Kidney Infection? What Causes Kidney Infection?

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.