Kidney infection

A kidney infection is caused by bacteria, often E. coli. They get into your urethra (the tube that you pee through) and move up to your bladder and ureter (the tube that connects your bladder to your kidneys) and then into your kidneys.

Often you will have a urinary tract infection (UTI) or cystitis (infection of your bladder) at the same time or before you have a kidney infection. However, you can develop a kidney infection without a UTI or cystitis if you have kidney stones, diabetes or a weakened immune system.  

Kidney infections tend to be more common in women than men. This is because a woman’s urethra is shorter, so the bacteria is more likely to reach the kidneys.

Pyelonephritis is more common if you:

• are pregnant
• are sexually active
• have diabetes
• have a catheter or any tubes in place to drain your bladder
• have kidney stones or other kidney problems
• have an enlarged prostate.

Your doctor will talk to you about your symptoms and examine you. If they think you might have a kidney infection, you may be asked to provide a urine (pee) sample to test for bacteria, blood or pus. Your doctor may also ask for a blood test that checks for bacteria or other organisms in your blood and a kidney function test. You may also need an ultrasound scan of your kidneys while you are sick or after you have recovered.

A kidney infection needs to be treated urgently with antibiotics. If it's not treated quickly, the infection can get worse and cause sepsis. This can cause permanent damage to your kidneys and can even lead to death.

The infection usually starts to clear up within a few days of taking the antibiotic, but you must take the entire course of antibiotics to make sure the infection is completely cleared.

Your antibiotic may need to be changed to a different one after few days if:

• you are not getting better or
• your urine test results show a different antibiotic is needed.

For a severe kidney infection, your doctor may admit you to the hospital. Treatment in hospital may include antibiotics that you receive through a vein in your arm (intravenously). You may also be prescribed medicine such as paracetamol for pain and fever.

It is helpful to drink plenty of fluids. This helps flush bacteria from your urinary tract. Avoid coffee and alcohol until your infection has cleared, as these can irritate your bladder.

The following simple measures can help to prevent kidney infections:

• Drink plenty of water to flush bacteria out of your urethra and bladder. Drink 1.5 to 2 litres a day and aim for pale yellow urine.
• Don't delay peeing – avoid 'holding on'.
• Make sure your bladder is as empty as possible every time you go.
• Women should always wipe from the front (vagina) to the back (anus) after going to the toilet.
• Pee before and soon after sexual intercourse.