Kidney infections are primarily caused by bacteria entering the urinary tract through the urethra and then traveling upward to infect the kidneys. The most common bacteria responsible are those normally found in the large intestine, such as Escherichia coli (E. coli), which can spread from the anus or vagina to the urethra and then ascend through the bladder and ureters to the kidneys
. Other causes and contributing factors include:
- Bacteria spreading through the bloodstream from infections elsewhere in the body, although this is less common
- Urinary tract blockages that slow or obstruct urine flow, such as kidney stones, an enlarged prostate, or structural abnormalities in the urinary tract, which facilitate bacterial growth and infection
- Use of urinary catheters, which can introduce bacteria directly into the urinary tract
- Weakened immune system due to conditions like diabetes, HIV, or immunosuppressive medications, increasing susceptibility to infection
- Nerve or spinal cord damage that impairs bladder sensation, potentially allowing infections to progress unnoticed
- Pregnancy, which can increase risk due to pressure on the urinary tract and hormonal changes
Women are more prone to kidney infections because their urethra is shorter and closer to the anus and vagina, making it easier for bacteria to enter the urinary tract. Sexual activity and hygiene practices can also influence risk
. In summary, kidney infections usually result from bacterial invasion ascending from the lower urinary tract, often facilitated by anatomical, physiological, or immune-related risk factors
