The most common cause of kidney infections is a urinary tract infection that spreads to one or both kidneys. Kidney infections can be acute or persistent. They're usually painful, and if not treated very away, they can be fatal. The medical term for a kidney infection is pyelonephritis.

Symptoms of a kidney infection typically develop two days after the infection has occurred. Depending on your age, your symptoms may differ. Symptoms that are common include:

1. Abdominal, back, groin, or side discomfort

2. A feeling of nausea or vomiting

3. The need to urinate frequently or the sensation of needing to urinate

4. Urinating with burning or pain

5. The presence of pus or blood in your urine

6. Urine with a foul odor or that is cloudy

7. Colds 

8. Fever

In your upper belly, you have two fist-sized kidneys, one on each side. They remove waste materials from your blood and deposit them in your urine. They also control the amount of water and electrolytes in your blood. Kidney function is critical to your overall health.

Most kidney infections are caused by bacteria or viruses that enter the urinary tract and invade the kidneys. Escherichia coli is a common bacterial cause (E. coli). These bacteria live in your intestine and can pass via the urethra into your urine tract. The urethra is the tube that transfers pee from your body to the outside world. The germs proliferate and travel to the bladder and kidneys from there.

- Bladder or kidney surgery is a procedure that involves the removal of a portion of the bladder or kidney

- A kidney stone or tumor in your urinary tract, an enlarged prostate in men, or an issue with the geometry of your urinary tract restricting urine flow.

A kidney infection can happen to anyone, however there are some conditions that make it more likely:

1. Pregnancy causes changes in the urinary tract, making it easier for bacteria to reach the kidneys.

2. Immune system deficiency. This includes persons who have diabetes, HIV, or AIDS, as well as those who are receiving immune-suppressing medications.

3. Damage to the spinal cord or bladder nerves may prevent you from noticing the signs of a urinary tract infection (UTI) that could lead to kidney infection.

4. Urinary retention is the inability to entirely empty your bladder. It can also happen to persons who have spina bifida or MS.

5. A cystoscope is a device that is used to examine the bladder.