Kidney infection

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 30, 2016
StartDiseasesKidney infection

Without immediate medical attention, a kidney infection (pyelonephritis) can cause permanent damage to the bladder, kidneys, and urinary system. The infection typically develops within the urethra and eventually travels up into the kidneys. Pyelonephritis almost always requires a battery of antibiotics while the patient recovers.


Definition & Facts

Kidney infections are a type of urinary tract infection. In rare cases, they can become severe and require hospitalization. They may infect one or both kidneys, and they are typically caused by E. coli, a type of bacteria that lives in one's colon. They are preventable in many cases. Avoiding douches and exercising proper hygiene following defecation as well as sexual activity can help prevent these infections.

Children, seniors over the age of 60, and women have the highest rates of kidney infections. Those who regularly develop kidney infections run the risk of experiencing secondary issues such as kidney stones and kidney failure. If left untreated, the infection can spread to the patient's bloodstream and cause a potentially fatal condition known as sepsis.

Symptoms & Complaints

The exact symptoms that a patient experiences depends on the severity of their infection. In the earliest stages, most patients complain of frequent urination or painful urination. As the infection progresses, pyelonephritis often causes symptoms that are similar to those of a common cold such as fever, chills, nausea, and vomiting.

Once the infection has spread to the kidneys, the patient will experience changes to their bladder habits. Debilitating pain along the flank and back pain are other symptoms that should not be ignored.

Anyone who notices unusual smells, cloudy urine, or blood in their urine should head to the emergency room for additional testing. Those who complain of these symptoms for more than 24 hours must seek out immediate medical attention.

While many of these issues can be caused by other medical complications, a patient should contact their doctor in order to be screened. Addressing a kidney infection in its earliest stages can help prevent permanent damage to a patient's kidneys.


Almost any condition that affects an individual's urinary tract can increase their risk of developing a kidney infection. For an uncomplicated kidney infection, the bacteria generally spreads from the end of the urethra. The bacteria will then reproduce within the bladder and spread up into the kidneys. This often takes place because of problems with one's hygiene habits including spreading pathogens from the anus to the urethra while wiping.

Bacteria that is found in the colon and digestive tract can infect the urethra and eventually the kidneys. As for elderly patients, the use of a catheter can increase their risk of a kidney infection as well. Those who have a compromised immune system tend to develop kidney infections at much higher rates.

Any issues that place stress on the kidneys will increase one's risk of an infection. That includes kidney stones that provide a place for the bacteria to grow. In rare cases, kidney infections can occur following surgery on the kidneys or other components of the urinary tract. Patients who have recently undergone surgery should be wary of any urinary issues or abnormalities including blood in their urine or frequent urination. 

Diagnosis & Tests

The vast majority of patients are tested for a kidney infection after complaining of one or more of the aforementioned common symptoms. If the doctor believes their patient has an infection, then they will most likely ask for a urine sample that can be tested for specific pathogens. Other substances within the urine such as pus or blood will also be tested for bacteria.

While the fluids are being tested, the doctor must give the patient a full physical examination to get a better idea about their overall health. That generally includes feeling their lymph nodes and checking for inflammation or tenderness near the kidneys.

A urine culture test might be carried out if any of the previous tests have come back with inconclusive results. During a urine culture test, the bacteria will be given time to thrive in a culture dish. By doing this, the doctor can better identify which antibiotics will be most effective in treating the infection.

Some doctors also suggest carrying out more comprehensive tests to ensure that additional damage has not taken place. Tests such as computed tomography (CT) scans and ultrasounds may be carried out if the patient has complained of any severe symptoms such as confusion or unbearable pain.

Treatment & Therapy

Antibiotics are almost always the first line of treatment for anyone who has been diagnosed with a kidney infection. The type of drugs that are used depends on a variety of different factors including what type of bacteria has been found in the patient's urine. While some patients require nothing more than a generic antibiotic, many benefit from personalized prescriptions developed from their urinalysis.

Most patients must stay on their antibiotics for at least seven to ten days in order to completely kill the pathogens. Going off of one's antibiotics too early can cause permanent damage to the urinary tract and make the kidney infection even worse. Those who have an ongoing fever or are dehydrated might need to stay in the hospital for a short period of time.

Prevention & Prophylaxis

Preventing a kidney infection rarely requires anything more than a few basic lifestyle changes including impeccable hygiene habits. A patient who is unsure of how to properly care for their urinary tract should speak with their doctor.

Drinking plenty of fluids and urinating frequently will help the body naturally clear pathogens out of the urinary tract. Those who are sexually active should empty their bladder after sexual intercourse to reduce their risk of an infection. Regularly using feminine hygiene products such as sprays and douches can cause urinary tract infections and thus should be avoided.