The causes of recurring, or recurrent, urinary tract infections may involve bacterial persistence in which the same bacterial organisms remain in the urinary tract, or reinfection, often by a different bacteria or other infectious organism. As defined by the "Oxford Handbook of Urology," recurrent urinary tract infections are infections that occur more than twice in a six-month period, or more than three times over a 12-month period. Causes of recurring urinary tract infections include anatomical or functional problems, and physical predisposition to those infections.
Anatomical Problems
Anatomical abnormalities can cause recurring urinary tract infections. A malformation of the valve at the ureterovesical junction may cause vesicoureteral reflux--the return of urine from the bladder into the ureters. Vesicoureteral reflux plays a role in 30 to 45 percent of cases of symptomatic urinary tract infections in young children, notes the Merck Manual for Healthcare Professionals. In women, a prolapsed uterus might play a role in recurring urinary tract infections, notes the "Oxford Textbook of Primary Medical Care." A condition known as a cystocele---a herniated bladder that bulges into the vagina---can predispose a woman to recurring urinary tract infections.
Kidney Stones
When kidney stones develop, they can provide a site for bacteria to congregate and multiply. That can result in recurring urinary tract infections caused by bacterial persistence. Resolution of the problem requires removal of the kidney stone.
Predisposition
Women who experience reinfections may have a physical predisposition for recurring urinary tract infections, explains the "Oxford Handbook of Urology." Their urogenital mucosa may be more vulnerable to the infectious agents that cause urinary tract infections. The "Oxford Textbook of Primary Medical Care" notes that during menopause, the mucosa might atrophy, leading to increased susceptibility to infections.
Enlarged Prostate
Long term or chronic bacterial infection of the prostate, known as bacterial prostatitis, remains the most common cause of recurring bladder infections in men, according to the Merck Manual for Healthcare professionals. The infected prostate becomes enlarged, and that can interfere with the emptying of the bladder. Incomplete voiding can facilitate the growth of bacteria in the urinary system and the occurrence of repeated infections.
Other Diseases, Treatments and Medications
Some health conditions, such as diabetes, can weaken the body's resistance to infection, and that might open the door to recurring urinary tract infections, notes the "Oxford Textbook of Primary Medical Care." Radiation treatments can also weaken the body's resistance, causing vulnerability to infections. Antibiotic medications and spermicides can alter the balance of organisms in the vaginal flora. This can allow overpopulation of certain bacteria, including E. coli, which can lead to recurring infections.
References
- "Oxford Handbook of Urology"; John Reynard, D.M., F.R.C.S. Urology; 2009
- "Oxford Textbook of Primary Medical Care"; Roger Jones; 2004
- Merck Manual for Healthcare Professionals: Bacterial Urinary Tract Infections
- National Guideline Clearinghouse: Guideline Summary
- National Kidney and Urologic Diseases Information Clearinghouse: Urinary Tract Infections in Adults
