A kidney infection happens when bacteria infects your kidneys. The bacteria are usually a type called
E. coli, which live in your bowel.
The bacteria get in through the opening of the urethra and move upwards through your urinary tract, first infecting your bladder and then your kidneys.
Causes of kidney infection
It’s thought the bacteria can get into your urinary tract by accidentally spreading from your anus to your urethra. This can happen if you wipe your bottom after going to the toilet and the soiled toilet paper comes into contact with your genitals. It can also happen during sex.
In rare cases, a kidney infection can develop if bacteria or fungi infect the skin and the infection spreads through your bloodstream into your kidney. However, this type of infection usually only occurs in people with weakened immune systems.