The urinary tract refers to the connected system of organs through which urine is processed and eliminated from the body. This includes the two kidneys, the two ureters (tubes that connect the kidneys to the bladder), the bladder, and the urethra (the tube from the bladder through which urine leaves the body). A urinary tract infection can affect any or all of these structures. A kidney infection (pyelonephritis) is generally discussed as a separate condition.
A urinary tract infection usually occurs when bacteria on the skin, or in the genital or rectal area enter the urinary tract via the urethra. If conditions are right, these bacteria can multiply within the urethra and bladder, causing infection. Sometimes infections begin during a medical procedure that requires placement of a catheter, a thin flexible tube that is inserted through the urethra and into the bladder, to drain urine. Some organisms can “climb” up the catheter into the bladder, resulting in a urinary tract infection. Sexual intercourse is another common trigger of urinary tract infections.
Many different kinds of bacteria can cause urinary tract infections, including:
Viruses can cause urinary tract infections in children.
On rare occasions, fungi may cause urinary tract infections.
Twenty percent of all women will have a UTI at some point in their lives. Men, throughout most of their adult lives, have a very low rate of urinary tract infections. Over the age of 50 however, their rate of infection reaches approximately that of women because prostate enlargement predisposes men to infection. This is due to incomplete emptying of the bladder. Urine that sits in the bladder increases the chance of bacterial growth. Researchers estimate that about 8-10 million visits to the doctor each year are for diagnosis and treatment of urinary tract infections.
Uncomplicated urinary tract infection (UTI) (pyelonephritis and cystitis). EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116894/Uncomplicated-urinary-tract-infection-UTI-pyelonephritis-and-cystitis. Updated July 8, 2016. Accessed October 6, 2016.
Urinary tract infections in adults. Urology Care Foundation website. Available at: http://www.urologyhealth.org/urologic-conditions/urinary-tract-infections-in-adults. Accessed September 17, 2014.
Urinary tract infections in adults. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: http://www.niddk.nih.gov/health-information/health-topics/urologic-disease/urinary-tract-infections-in-adults/Pages/facts.aspx. Updated May 24, 2012. Accessed September 17, 2014.
Last reviewed September 2017 by Adrienne Carmack, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.