Kidney infection

A kidney infection usually occurs when a bacterial infection (typically e-coli bacteria) moves up from the bladder or urethra and into one of the kidneys. The urethra is the tube that runs from the bladder through the penis or vulva. Urine is passed through the urethra.

The medical term for a kidney infection is pyelonephritis. Typical symptoms of a kidney infection can include:

• a high temperature (fever) of 38ºC (100.4ºF) or above,
• pain in the side of your abdomen,
• vomiting, and
• diarrhoea.

The kidneys

The kidneys are two bean-shaped organs that are located on either side of the body, just underneath the ribcage. The main role of the kidneys is to filter out waste products from the blood before converting it into urine.

Usually, only one kidney is affected by an infection.

How common are kidney infections?

Kidney infections are more common in:

• women than in men,
• pregnant women,
• children who are under two,
• people over 60.

Types of kidney infection

There are two main types of kidney infection:

• Uncomplicated kidney infection: the person is in good health and the infection is unlikely to cause any serious complications.
• Complicated kidney infection: the person affected is more vulnerable to the effects of infections. This could be due to a pre-existing health condition.

Outlook

In cases of uncomplicated kidney infection, treatment with antibiotics quickly relieves symptoms, and most people will fully recover within two weeks.

In cases of complicated kidney infection, treatment usually requires injections of antibiotics (intravenous antibiotics), and the person may be admitted to hospital as a precaution.

There is a small risk of serious complications developing in complicated kidney infection, such as blood poisoning (sepsis) or a kidney abscess, which can occasionally be life threatening.

There is also the risk that the kidney could become damaged as a result of the infection and, in the most serious cases, the damage could cause the kidney to stop working altogether (kidney failure).

Despite the risk of complications, deaths from kidney infections are now very rare. This is mainly due to the introduction of antibiotics in the 1940s.

Glossary

Kidneys

Kidneys are a pair of bean-shaped organs located at the back of the abdomen. They remove waste and extra fluid from the blood, and pass them out of the body as urine.

Bladder

The bladder is a small organ near the pelvis that holds urine until it is ready to be passed from the body.

Bacteria

Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease, and some are good for you.