Overview

Pyelonephritis, or kidney infection, is a serious type of urinary tract infection that can affect one or both kidneys. It usually happens when bacteria move up from the bladder through the ureters and into the kidneys. Infection can severely damage the kidneys' ability to filter waste products and maintain fluid balance if left untreated. Kidney infections can come on suddenly and get worse quickly if they aren't treated right away. Most cases respond well to antibiotics, but if treatment is delayed, it can lead to complications such as kidney damage or bloodstream infection.

Symptoms
Common signs include a high fever, chills, back or side pain, nausea, vomiting, and frequent, painful urination. The urine may look cloudy, smell bad, or contain blood. People may also feel tired and weak all over. Confusion or low blood pressure may happen in severe cases, especially in older adults.

Causes
Escherichia coli and other bacteria that normally live in the intestines are the most common causes of kidney infections. Risk factors can include untreated bladder infections, urinary tract obstruction due to stones or an enlarged prostate, compromised immunity, pregnancy, and the utilization of urinary catheters.

Diagnosis
To make a diagnosis, doctors test urine for bacteria, white blood cells, and blood. A urine culture finds the exact organism. Blood tests check how bad an infection is and how well the kidneys are working. If there are signs of complications or an obstruction, imaging tests such as an ultrasound or a CT scan may be performed.

Treatment
To get rid of the infection, treatment needs to start right away with antibiotics. Oral antibiotics can be used to treat mild cases, but severe cases require hospitalization and IV medication. Getting enough fluids helps you get better. It is important to treat the underlying causes, such as a urinary tract blockage. 

Early treatment usually leads to a good outcome for kidney infections. Most people fully recover and don't have any long-term effects. Delayed or untreated infections can lead to kidney scarring or systemic infection, underscoring the importance of getting care right away