Pyelonephritis, infection, and inflammation of the kidney tissue occur when a urinary tract infection has traveled to the upper urinary tract (which includes the ureters and the kidneys). The infection is usually bacterial. The most common type of renal disorder, pyelonephritis may be chronic or acute.
In acute pyelonephritis the lining of the renal structures into which urine drains, the renal pelvis and the calyces, may be inflamed. Abscesses may form in the kidney tissue, and some of the urine-producing structures may be destroyed. Medical treatment will fight the infection over a period of one to three weeks. Scar tissue will form at the site of infection, but there is usually sufficient healthy tissue to maintain relatively normal renal functions. Acute pyelonephritis symptoms usually include fever, chills, pain or aches in the lower back and flanks, bladder inflammation, tenderness in the kidney region, white blood cells in the urine, and a high urine bacterial count. Treatment usually requires suppression of bacterial growth by means of antibiotic drugs. Frequent sexual intercourse is listed as a cause of UTIs and a risk factor for acute pyelonephritis.
Chronic pyelonephritis results from bacterial infections in the kidneys over a period of years. Each episode of infection may pass unnoticed but may destroy more and more areas of tissue until the amount of functional kidney tissue is far less than the scar tissue that has formed. Active infections are treated with antibacterial drugs.
It is a more serious condition than ordinary urinary tract infections, which typically only affect the urethra and bladder.
The primary job of the kidneys is to filter waste from the bloodstream, producing urine that travels down the ureters and into the bladder. The bladder voids the urine out of the body through the urethra.
Women are more likely than men to get urinary tract infections and pyelonephritis. This is because a woman’s urethra is shorter than a man’s, so it is comparatively easier for bacteria to travel to the urinary tract organs.
An untreated infection can damage the kidneys and lead to long term problems. In some rare cases, kidney infections can lead to kidney disease, high blood pressure, or kidney failure. If kidney infection spreads to the bloodstream it can cause a serious problem called sepsis.
Most kidney infections begin as lower urinary tract infections, which worsen as they progress up the urinary tract. The symptoms of a UTI include:
- Painful, stinging or burning sensation with urination (dysuria)
- Urinary frequency
- Persistent urge to urinate, even after the bladder has just been emptied
The symptoms of a urinary tract infection, plus these additional symptoms, may indicate a case of pyelonephritis:
- Fever, chills, nausea, abdominal pain and/or vomiting
- Back pain or flank pain
- Disorientation or confusion (especially in seniors)
- Changes in the urine (bloody, cloudy, or smelly)
Pyelonephritis is usually caused by the same bacteria that cause a typical urinary tract infection: the bacteria found in the colon. These bacteria can live on the skin surrounding the anus, and can sometimes get into the urinary tract. Better hygienic habits can help prevent the spread of these bacteria.
Although our urinary system is designed to keep bacteria out, problems can occur. Escherichia coli (E. coli) or other dangerous bacteria that can cause infectious diseases found in the intestines can enter the urinary tract through the urethra. In vesicoureteral reflux, these bacteria can travel up into the bladder, which can cause cystitis (inflammation of the bladder). It can also cause urinary tract infection. Cystitis occurs in 1-3% of adult women per year. If the infection continues up to the kidneys, it can cause a kidney infection. This problem is rare but it can be severe. 1 in every 30 cases of UTI leads to a kidney infection.
If you have frequent bladder infections or have a structural problem in the urinary tract, you are more likely a candidate to contract kidney infection. Normally flow of urine goes only in one direction—from the kidneys to the bladder. If the flow of urine is blocked or flows in the wrong direction, infections can happen. Urine flow can be blocked by many things, including:
- Bladder, ureter or kidney stones
- Tumors in the abdomen or pelvis
- Birth defects that affect the shape of the urinary tract
People with diabetes or a weak immune system are at high risk for infections. Pregnant women with UTIs should be seen by their health care provider and treated as soon as possible. A kidney infection in a pregnant woman can be very serious.
Additionally, if the immune system is suppressed, the body is less likely to be able to fight off a kidney infection. Some conditions that suppress the immune system include:
- Immunosuppressant medication, such as those after an organ transplant
- Immune disorders
If you’re experiencing symptoms of pyelonephritis, make an appointment with your doctor right away. Your doctor will conduct a physical examination and may perform one or more tests to confirm your diagnosis.
You will be asked to provide a urine sample, which the lab technicians will examine under a microscope. If your urine contains too many white blood cells or bacteria, you may have a UTI or pyelonephritis.
Your doctor can grow a culture using the bacteria found in your urine. This can help identify the type of bacteria living in your urinary tract.
If a bacterial infection is found in the blood culture, this may be an indication of severe or acute pyelonephritis.
An ultrasound can be used to detect stones or other masses in your pelvis.
Computed tomography (CT) scan
CTs scans use X-rays to create a 3-D image of your internal organs, which can be helpful in diagnosing pyelonephritis.
Treating for Pyelonephritis
Because pyelonephritis is a potentially serious medical condition, doctors recommend medical intervention right away. Fortunately, pyelonephritis can be treated very effectively with a seven-day regimen of oral antibiotics. Most patients can take oral antibiotics at home.
However, patients who are vomiting will not be able to keep oral antibiotics medications down. In addition, people who are disabled or confined to a bed may have a hard time taking care of themselves without extra help. In these cases, it’s recommended that the patient is hospitalized and receives intravenous antibiotics.
Abscesses are small “pockets” of infected tissue that can sometimes form in serious cases of pyelonephritis. They must be drained through a tube inserted through the skin and into the kidney, with the help of a healthcare provider.
Chronic Kidney Infections
Although most cases of pyelonephritis occur on a singular basis and do not persist after successful treatment, some patients may suffer from chronic pyelonephritis.
Chronic pyelonephritis usually results from a congenital defect in the kidneys characterized by extensive scarring and degeneration. The condition is usually found in children. If you or your child is diagnosed with chronic pyelonephritis, your doctor will refer you to a specialist in renal care.