• Knowledgebase: Information on Specific Illnesses

    Here you will find discussions of specific illnesses and their management.

    50. Kidney Infection - Top

    Definition
    An infection of the kidney and the ducts that carry urine away from the kidney (ureters).

    Causes, Incidence and Risk Factors
    Pyelonephritis can be further classified according to the extent and severity of damage to the kidneys. Types include:

    reflux nephropathy
    acute uncomplicated pyelonephritis (sudden development of kidney inflammation)
    complicated UTI (chronic pyelonephritis)
    Pyelonephritis most commonly occurs as a result of urinary tract infection (cystitis), particularly in the presence of transient (occasional) or persistent backflow of urine from the bladder into the ureters or kidney pelvis (vesicoureteric reflux ).
    Although cystitis (bladder infection) is common, pyelonephritis occurs much less often. The incidence of pyelonephritis is approximately 3 to 7 out of 10,000 people. The risk is increased if there is a history of cystitis, renal papillary necrosis, kidney stones, vesicoureteric reflux, or obstructive uropathy. The risk is also increased when there is a history of chronic or recurrent urinary tract infection, and when the infection is caused by a particularly virulent bacteria.
    Acute pyelonephritis can be severe in the elderly and in people who are immunosuppressed (for example, those with cancer or AIDS).


    Symptoms
    flank pain or back pain
    severe abdominal pain (occurs occasionally)
    fever
    higher than 102 degrees Fahrenheit
    persists for more than 2 days
    chills with shaking
    warm skin
    flushed or reddened skin
    moist skin (diaphoresis)
    vomiting, nausea
    fatigue
    general ill feeling
    urination, painful
    urinary frequency/urgency, increased
    need to urinate at night (nocturia)
    cloudy or abnormal urine color
    blood in the urine
    foul or strong urine odor
    mental changes or confusion *
    * Often in the elderly person, mental changes or confusion are the only signs of a possible urinary tract infection.

    Signs And Tests
    An examination may show tenderness on palpation (pressing) over the kidney.


    A urinalysis commonly reveals white blood cells (WBC) and/or red blood cells (RBC).
    A urine culture (clean catch) or urine culture (catheterized specimen) may reveal bacteria in the urine.
    A blood culture may show an infection with gram-negative organisms.
    An IVP or CT scan of the abdomen may show enlarged kidney(s) with decreased excretion of contrast. (IVP and CT scan of the abdomen can also indicate underlying disorders.)
    Underlying disorders predisposing a patient to acute pyelonephritis may be discovered by other tests and procedures, including:

    voiding cystourethrogram
    renal ultrasound
    renal scan
    renal biopsy



    Treatment
    The goals of treatment are control (cure) of the infection and reduction of symptoms. Acute symptoms usually persist longer than 48 hours after treatment is begun.
    Also, due to the high mortality rate in the elderly population, and the risk of permanent kidney damage, prompt treatment is recommended.
    Initial therapy usually consists of obtaining a urine culture to identify the causative organism, and selecting appropriate antibiotics to treat that infection. However, it may take 3 to 5 days to receive urine culture results. In the interim, you will usually be hospitalized to receive broad spectrum IV (intravenous) antibiotics and monitoring of kidney function.
    MEDICATIONS:
    Intravenous (IV) antibiotics may be used initially to control the bacterial infection. In acute cases of pyelonephritis, you will receive a ten to fourteen day course of antibiotics, however, chronic pyelonephritis may require long-term antibiotic therapy. It is imperative that you finish taking the entire course of prescribed antibiotics. Commonly used antibiotics include:

    furidantin
    sulfa drugs
    amoxicillin
    cephalosporins
    sulfisoxazole/trimethoprim
    doxycycline
    Kidney damage can result from these infections. Also, the elderly, infants, and immunocompromised people are at increased risk for developing sepsis (a severe blood infection). Often, these people will be admitted to the hospital to receive frequent monitoring for potential problems, and to receive IV antibiotics, additional IV fluids and other medications as necessary. In severe cases, a person may be placed in the intensive care unit to receive even more intense monitoring, especially if any cardiac problems are noted.
    SURGERY:
    Surgery is generally not indicated in the presence of a urinary tract infection.
    LIFESTYLE CHANGES:
    Preventive measures may reduce symptoms and prevent recurrence of infection. Keeping the genital area clean and remembering to wipe from front to back may reduce the chance of dragging E. coli bacteria from the rectal area to the urethra.
    Urinating immediately after sexual intercourse may help eliminate any bacteria that may have been introduced during intercourse. Refraining from urinating for long period of time may allow bacteria time to multiply, so frequent urination may reduce the risk of cystitis in those who are prone to urinary tract infections.
    DIET:
    Increasing the intake of fluids (2000 to 4000 cc per day) encourages frequent urination that flushes bacteria from the bladder. Avoid fluids that irritate the bladder, such as alcohol, citrus juices, and caffeine.
    MONITORING:
    Follow-up should include a urine culture at the completion of antibiotic therapy to ensure that bacteria are no longer present in the urine.

    Expectations (Prognosis)
    Most cases of pyelonephritis resolve without complication after the treatment. However, the treatment may need to be aggressive or prolonged
    - Updated: March 5, 2001

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    • James L Horwitz, MD

    David C. Thomas, MD

    Barbara Lindberg, PNP