A urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract.The main causitive agent is:Escherichia coli. Although urine contains a variety of fluids, salts, and waste products, it usually does not have bacteria in it. When bacteria get into the bladder or kidney and multiply in the urine, they cause a UTI. The most common type of UTI is a bladder infection which is also often called cystitis. Another kind of UTI is a kidney infection, known as pyelonephritis, and is much more serious. Although they cause discomfort, urinary tract infections can usually be quickly and easily treated with a short course of antibiotics.
UTIs are most common in sexually active women and increase in diabetics and people with sickle-cell disease or anatomical malformations of the urinary tract.
Since bacteria can enter the urinary tract through the urethra (an ascending infection), poor toilet habits (such as wiping back to front for women) can predispose to infection, but other factors (pregnancy in women, prostate enlargement in men) are also important and in many cases the initiating event is unclear.
While ascending infections are generally the rule for lower urinary tract infections and cystitis, the same may not necessarily be true for upper urinary tract infections like pyelonephritis which may be hematogenous in origin.
Allergies can be a hidden factor in urinary tract infections. For example, allergies to foods can irritate the bladder wall and increase susceptibility to urinary tract infections. Urinary tract infections after sexual intercourse can also be due to an allergy to latex condoms, spermicides, or oral contraceptives. In this case review alternative methods of birth control with your doctor.
Staphylococcus epidermidis is commonest in patients using urinary catheters. Indwelling urinary catheters in women and men who are elderly, over placement of a temporary prostatic stent can be a major cause of UTIs. Also, people experiencing nervous system disorders, people who are convalescing or unconscious for long periods of time, will have an increased risk of urinary tract infection for a number of reasons. Scrupulous aseptic techniques may decrease these associated risks.
The bladder wall is coated with various mannosylated proteins, such as Tamm-Horsfall proteins (THP), which interfere with the binding of bacteria to the uroepithelium. As binding is an important factor in establishing pathogenicity for these organisms, its disruption results in reduced capacity for invasion of the tissues. Moreover, the unbound bacteria are more easily removed when voiding. The use of urinary catheters (or other physical trauma) may physically disturb this protective lining, thereby allowing bacteria to invade the exposed epithelium.
Elderly individuals, both men and women, are more likely to harbor bacteria in their genitourinary system at any time. These bacteria may be associated with symptoms and thus require treatment with an antibiotic. The presence of bacteria in the urinary tract of older adults, without symptoms or associated consequences, is also a well recognized phenomenon which may not require antibiotics. This is usually referred to as asymptomatic bacteriuria. The overuse of antibiotics in the context of bacteriuria among the elderly is a concerning and controversial issue.
Women are more prone to UTIs than men because in females, the urethra is much shorter and closer to the anus than in males, and they lack the bacteriostatic properties of prostatic secretions. Among the elderly, UTI frequency is in roughly equal proportions in women and men.
A common cause of UTI is an increase in sexual activity, such as vigorous sexual intercourse with a new partner, although the reason behind this is unclear. The term "honeymoon cystitis" has been applied to this phenomenon.
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Last Updated: May 14, 2013