Kidney infection

A kidney infection is a painful and unpleasant condition that usually occurs when bacteria from the bladder travel to one or both kidneys.

In medical literature, kidney infection is referred to as pyelonephritis. This is a more serious and different condition from cystitis, which is a common bladder infection in which a person has painful urination.

If treated properly, kidney infection does not cause serious harm, but if not treated in time, the condition can worsen and lead to permanent kidney damage.

Symptoms of a kidney infection often appear within a few hours. You may feel fever, shivering, nausea, back or side pain.

A kidney infection usually occurs when bacteria, often a type of E. coli, enter the urethra (the tube that carries urine out of the body) from the anus and travel upward to the bladder and then to one or both kidneys.

Symptoms of kidney infection

Symptoms of kidney infection usually develop fairly quickly, within a few hours or days.

Common symptoms include:

• Flank pain;
• Pain and discomfort in the lower back or groin area;
• High fever;
• Shivering;
• Chills;
• Feeling very weak or tired;
• Loss of appetite;
• Nausea;
• Vomiting;
• Diarrhea.

In the case of cystitis or urethritis (urethral infection), you may experience other symptoms.

These additional symptoms may include:

• Pain or burning when urinating;
• Needing to urinate suddenly or more often than usual;
• Feeling like you can't empty your bladder completely;
• Blood in the urine;
• Smelly  or cloudy urine;
• Pain in the lower abdomen.

Causes of kidney infection

A kidney infection occurs when bacteria enter one or both kidneys and infect them. The bacteria enter the lumen of the ureter and travel up the urinary tract, first infecting the bladder and then the kidneys.

It has been suggested that one route for bacteria to enter the urethra is by accidental entry into the urethra from the anus. This can occur when soiled toilet paper touches the genitals after using the toilet.

In rare cases, a kidney infection can develop when a bacterium or fungus infects the skin and the infection spreads through the bloodstream to the kidneys. However, this form of infection usually occurs in people with weakened immune systems.

Complications of kidney infection

Most kidney infections are successfully treated without complications, although some patients may develop additional problems

Kidney abscess

Kidney abscess is a rare condition that is a serious complication of kidney infection. This is when pus forms in the tissues of the kidney. Patients with diabetes have the highest risk of developing a kidney abscess.

The symptoms of a kidney abscess can be similar to those of a kidney infection. The most common of these are:

• Fever;
• Chills;
• Abdominal pain;
• Loss of appetite;
• Pain when urinating.

Blood poisoning

Blood poisoning (also known as sepsis) is another complication of kidney infection. It develops when bacteria travel from the kidneys into the bloodstream. Once the bacteria enter the blood, the infection can spread to any part of the body, including major organs.

In a patient with a kidney infection, signs of blood infection may include the following:

• Low blood pressure, which causes dizziness when standing up
• Confusion or disorientation;
• Excessive sweating;
• Involuntary uncontrollable shivering;
• Fever or a lower than normal body temperature;
• Pale skin;
• Rapid heartbeat;
• Shortness of breath.

Severe infection

Another complication of kidney infection is emphysematous pyelonephritis. This is a severe infection in which the kidney tissue is rapidly damaged and the bacteria causing the infection begin to release toxic gas that builds up in the kidneys. The exact cause of EPN is unknown, but almost all cases occur in people with diabetes. The usual treatment is immediate surgical excision of the affected kidney or part of it. You can live a full and active life with one kidney.

Kidney failure

In very rare cases, a kidney infection can cause severe kidney damage, eventually leading to kidney failure.

When to see a doctor

See your doctor if you have a fever, abdominal, lower back or groin pain, or if you notice changes in your urination habits. Most kidney infections require immediate antibiotic treatment to prevent kidney damage or the spread of infection through the bloodstream.