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Urinary tract infections (UTIs) are one of the most common clinical problems worldwide and can result in significant morbidity. They affect 50% of adult women in their lifetime and 25% to 30% will have a recurrent infection.1 The prevalence of UTI increases with age affecting 1% of female infants, 3% to 5% of adult women, and up to 50% of elderly men and women.2 It is the single most common cause of nosocomial infection associated with the use of indwelling catheters and can result in life-threatening sepsis.3,4 Worldwide, it is estimated that 150 million cases occur per year5 presenting a huge burden on health care resources.


A UTI is defined as inflammation of the urinary tract due to microbial invasion of the urinary tract that presents as a number of clinical syndromes including cystitis, pyelonephritis, and urethritis. In this chapter we cover asymptomatic bacteriuria (ASB), urethritis, cystitis, pyelonephritis, and to a limited extent sexually transmitted diseases (STDs).


Key Points

  • Asymptomatic bacteriuria is defined as the presence of bacteria without associated inflammation in the urinary tract.

  • Cystitis and pyelonephritis are inflammations of the bladder and renal parenchyma usually caused by microbial invasion.


Definitions: Bacteria may be present in the urinary tract without associated inflammation and this is termed ASB. Urethritis is inflammation of the urethra for which there are a wide variety of causes including microbial invasion (eg, STDs), trauma, fungal infection, and allergy. Cystitis and pyelonephritis are inflammations of the bladder and renal parenchyma, respectively, and are most frequently, but not always, caused by microbial invasion (usually by bacteria) (Table 17-1). Most infections are sporadic, occur in patients without identified comorbidities or anatomical abnormalities of the urinary tract, and involve the lower urinary tract. In the 25% to 30% of women who develop UTI recurrence most cases are unrelated to an underlying anatomical or functional abnormality.1,6 A complicated UTI is a UTI associated with functional or anatomical abnormalities of the urinary tract that increase the risk of serious complications or treatment failure, such as conditions that cause obstruction or relative stasis of urinary flow.

Table Graphic Jump Location
Table 17-1

Definitions of Bacteriuria




Natural History


In children up to one year of age 1.1% of girls and 1.2% of boys may suffer a symptomatic UTI. In school-age children a UTI has been reported in 8% of girls and 2% of boys.7 UTI in the neonate should be considered to be secondary to an underlying anatomical abnormality ...

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