A kidney infection, known medically as pyelonephritis, often occurs when a urinary tract infection, or UTI, spreads up the ureters to the kidneys. Kidney infections are more serious than UTIs and can cause life-threatening infections in some cases. While cranberry juice may help prevent UTIs, it has no benefit in curing kidney infections. Kidney infections require medical treatment with antibiotics.
The kidneys connect to the bladder with two long tubelike structures called ureters. Many kidney infections are ascending infections from the bladder. UTIs that affect only the bladder are common ailments, especially for a woman, who has a shorter urethra, the tube that leads to the bladder. Because the urethra lies in close proximity to the rectum, bacteria from the rectum can easily enter the urethra and reach the bladder. Taking cranberry in juice or pill form may prevent UTIs by making it hard for bacteria to stick to the walls of the bladder and also by making the urine more acidic, according to the website of DaVita dialysis centers.
Researchers from the University of Minnesota published an article in the 2009 issue of "Drugs" on the use of cranberry to treat UTIs. A review of previous studies showed no benefit in treating UTIs with cranberry, so more focus has been placed on its benefit in prevention. Even there, study results are mixed, depending on the type of infection and the population. In lab and animal studies, cranberry has been beneficial. Recurrence rates over a 12-month period are reduced by around 35 percent in young to middle-aged women -- but in older patients or people with neurogenic bladder or indwelling catheters, benefit is questionable. The Cochrane Collaboration, a health-care review organization, supports the potential use of cranberry to prevent -- not treat -- UTIs. University of Minnesota researchers state that lack of standardization of dosage and type of product make recommending cranberry for prophylaxis difficult without further studies.
Kidney Infection Symptoms and Risks
Kidney infections can cause serious damage to the kidney. Signs of kidney infection include pain in the back -- on either side of the body, with tenderness to the touch -- and nausea, vomiting, fever, chills and malaise. Urine may contain blood or pus. A person with a kidney infection normally feels quite ill and may require hospitalization to prevent the infection from spreading to the bloodstream.
Do not delay medical treatment while trying cranberry as a cure for a kidney infection, or you may become seriously ill with an infection in the blood. Reducing bacteria levels in the bladder with cranberry will not cure an existing kidney infection, although it may help to prevent recurrent UTIs. Kidney infections require longer therapy than bladder infections, often requiring a 14-day course of antibiotics, according to Dr. Neal Chamberalin of A.T. Still University.