Kidney Infections Health Article

Definition

Kidney infection is a general term used to describe infection of the kidney by bacteria, fungi, or viruses. The infecting microbe may have invaded the kidney from the urinary bladder or from the bloodstream. The disease is characterized by fever, chills, back pain, and, often, the symptoms associated with bladder infection.

Description

As the principle part of the urinary system, the kidneys process the fluid component of blood (called plasma) to maintain appropriate water volume and concentrations of chemicals. The waste product formed from this process is called urine. Urine travels from the kidney, through tubes called ureters, to the urinary bladder, and is eliminated from the body through a tube called the urethra. The kidneys and ureters comprise the upper urinary tract, and the bladder and urethra comprise the lower urinary tract.

Kidney infection, also called pyelonephritis and upper urinary tract infection, occurs when microbes, usually bacteria, invade the tissues of the kidney and multiply. One or both kidneys may be infected. Infection originating directly from the bladder is called an ascending infection.

Inflammation occurs in response to the infection. As a result of the infection and inflammation, scarring and other tissue damage may occur. Most cases of acute kidney infection resolve without any permanent kidney damage. In severe cases, kidney damage is so extensive that the kidneys can no longer function, a state called renal failure.

Types of kidney infections:

• Acute pyelonephritis: uncomplicated kidney infection that has a short and relatively severe course.
• Chronic pyelonephritis: long-standing disease associated with either active or inactive (healed) kidney infection.
• Emphysematous pyelonephritis: acute infection associated with gas in and around the kidney. This type almost always occurs in persons with diabetes.
• Pyonephrosis: acute or chronic pyelonephritis associated with blockage of the ureter.
• Renal and perinephric abscesses: abscesses (pockets of pus) in and around the kidney.

Kidney infections occur most often in adult females who are otherwise healthy. Urinary tract infections are uncommon in males until old age, when bladder catheterization and other urinary procedures are more commonly performed.