A urinary tract infection or UTI is caused by bacterial proliferation in the bladder, kidneys or connective tubing through which urine flows. UTIs are caused most commonly by bacterial infection of the bladder or kidneys, leading to proliferation of bacteria in the urine. Symptoms include frequent urination, cloudy urine and pain upon urine excretion.
Types
Infection of the bladder or urethra, the tube through which urine flows from the bladder to the outside of the body, is referred to as a lower UTI. Infection of the kidneys or ureter, the tube through which urine flows between the kidneys and the bladder, is defined as an upper UTI, according to a September 2007 article published by the Merck Manuals Online Medical Library.
Pathogenesis
By far the most common pathogen responsible for UTIs is E. coli, which is implicated in 80 to 85 percent of all cases. Staphylococcus saprophyticus causes 5 to 10 percent. Entry of these bacteria into the urethra and subsequent proliferation up this tube may lead to infection of the bladder, ureters, and in severe cases the kidneys if left untreated, according to the Mayo Clinic.
Gender
The frequency and severity of UTIs is 50 times greater in women than in men because of a combination of factors. The anus and urethra are much closer together in women, increasing the likelihood of bacterial transfer leading to infection of the urethra. Men are additionally protected from UTIs because of the presence of antibacterial secretions from the prostate gland in urine. The shorter length of the female urethra increases the risk that infections will progress from the urethra to the bladder, leading to more severe UTIs, according to the British National Health Service.
Sex
About 75 to 90 percent of UTIs in young women are related to sexual activity, with the risk of infection rising in proportion to the frequency of sex, according to a February 2008 article published in the Urological Clinics of North America.
Treatment and Morbidity
Lower UTIs usually heal spontaneously but may progress to the upper urinary tract if left untreated. For this reason, the patient is usually prescribed with antibiotics such as cotrimoxazole or ciprofloxacin, which are active against bacteria such as E. coli. Upper UTIs are potentially extremely serious because permanent damage to the kidneys may result possibly leading to the requirement for lifelong kidney dialysis if the patient is not prescribed antibiotics immediately. Death of between 1 and 3 percent of patients occurs as a result of upper UTIs, and factors correlated with a poor prognosis include old age, disability, sickle cell anemia, diabetes and cancer, according to a November 2009 article published on eMedicine.
References
- Urological Clinics of North America: Uncomplicated Urinary Tract Infection in Adults Including Uncomplicated Pyelonephritis; L. Nicolle; February 2008
- NetDoctor: Urinary Tract Infectons, Adults
- eMedicine: Urinary Tract Infection, Female
- Mayo Clinic: Urinary tract infection
- Merck Manuals Online Medical Library: Bladder Infection (Cystitis)
