Urinary Tract Infection - Introduction

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Complicated Urinary Tract Infections

Complicated UTIs may develop because of any one of a number of physical problems and affect any gender and age group. The common feature in most complicated UTIs is the inability of the urinary tract to clear out bacteria because of a physical condition that causes obstruction to the flow of urine or problems that hinder treatment success.

Recurrent Urinary Tract Infections

Most women who have had an uncomplicated UTI have occasional recurrences. A 25 - 50% of these women can expect another infection within a year of the previous one. Between 3 - 5% of women have ongoing, recurrent urinary tract infections, which follow the resolution of a previous treated or untreated episode.

Recurrence is often categorized as either reinfection or relapse:

• Reinfection. About 80% of recurring UTIs are reinfections. A reinfection occurs several weeks after antibiotic treatment has cleared up the initial episode and can be caused by the same bacterial strain that caused the original episode or a different one. The infecting organism is usually introduced through the rectal region from fecal matter and moves up through the urinary tract.
• Relapse. Relapse is the less common form of recurrent urinary tract infection. It is diagnosed when a UTI recurs within 2 weeks of treatment of the first episode and is due to treatment failure. Relapse usually occurs in kidney infection (pyelonephritis) or is associated with obstructions such as kidney stones, structural abnormalities or, in men, chronic prostatitis.

Asymptomatic Urinary Tract Infection (Asymptomatic Bacteriuria)

When a person has no symptoms of infection but significant numbers of bacteria have colonized the urinary tract, the condition is called asymptomatic UTI (also called asymptomatic bacteriuria). (In general, there must be at least 100,000 bacteria per milliliter of urine.) The condition is harmless in most people and rarely persists, although it does increase the risk for developing symptomatic UTIs.

Screening for asymptomatic bacteriuria is not necessary during most routine medical examinations, with the following exceptions: