What Causes a Kidney Infection?
Kidney and urinary tract infections may be caused by bacteria invading the urine, which is normally a sterile body fluid. Bacteria most commonly gain access to the urine through the urethra, which can be exposed to bacteria from outside of the body.
Common sources of bacteria that enter the urinary system are the vagina, anus, and skin. Because of the shorter length of the urethra in women, urinary tract infections are more common in women compared to men. Some factors may predispose certain people to urinary tract infections.
Sexual intercourse may increase the risk of urinary tract infections in women. Kidney infection may be facilitated by the introduction of bacteria from outside (vagina) to the urinary system through the urethra.
Pregnant women may be at higher risk for developing urinary tract infections. This may be caused by increased pressure on the ureters from the enlarged uterus. Approximately 10% of pregnant women may develop kidney and urinary tract infections during their pregnancy.
Kidney stones are another factor that may increase the likelihood of urinary tract infection. Stones can cause partial or complete obstruction to the flow of urine from the kidneys and ureters. This obstruction may act as a focus of infection in the urinary system, leading to urinary tract infections.
Bladder catheters (Foley catheters) are sometimes placed into the bladder in order to aid the outflow of urine from the bladder. There are many uses for bladder catheters, for example, paralysis with nerve damage, bladder obstruction from an enlarged prostate, or immobilized or hospitalized patients who are not able to independently urinate. These catheters may act as a vehicle for bacteria to gain access to the urine inside the bladder causing urinary infections.
In children, some risk factors include female gender, an uncircumcised male, or a structural abnormality of the urinary system.
The most common bacteria causing urinary tract infection or kidney infection are those that are normally seen in the vagina, gastrointestinal tract, or skin. By far, the most common organism causing urinary tract infection is Escherichia coli (E. coli), responsible for up to 80% of kidney and urinary infections. Other common bacteria include Klebsiella, Proteus, Pseudomonas, Enterococcus, and Staphylococcus saprophyticus.
When to Go to the Doctor If You Think You Have a Kidney Infection
If symptoms suggestive of urinary tract or kidney infection are present, medical attention should be sought. Correct diagnosis of kidney infection is important because it will determine appropriate therapy and length of treatment.
Once the doctor diagnoses kidney infection, home therapy with antibiotics and adequate oral intake of food and fluid may be adequate. In severe cases of infection or uncontrolled nausea and vomiting, hospitalization may be necessary.