Upon completion of the chapter, the reader will be able to:
Determine the diagnostic criteria for significant bacteriuria.
Interpret the signs and symptoms of urinary tract infections (UTIs) and differentiate those of upper versus lower urinary tract disease.
Identify the organism responsible for the majority of uncomplicated UTIs.
Assess the laboratory tests that help in diagnosing patients with UTI.
Recommend appropriate drug, dose, and duration for uncomplicated and complicated UTI prophylaxis and empiric treatment.
Evaluate and select therapy for uncomplicated and complicated UTIs based on specific urine culture results and patient characteristics.
Formulate appropriate monitoring and education information for patients with UTIs.
Urinary tract infections (UTIs) are comprised of a diverse array of syndromes depending on the location of the infection within the urinary tract.1,2,3 UTIs are one of the most common infectious diseases accounting for approximately 10.5 million annual ambulatory patient visits.4 In hospitalized patients, UTIs are also common and are reported in 3.7% of catheterized and 0.9% of non-catheterized patients.5 A UTI is defined by microorganism(s) in the urinary tract, which does not represent contamination.
EPIDEMIOLOGY AND ETIOLOGY
The prevalence and type of UTIs generally vary by age and gender.7,8 Premature infants have a higher rate than full-term infants, and neonatal boys are five to eight times more likely to have UTIs than neonatal girls. In young children 1 to 5 years of age, significant bacteriuria occurs more in girls than boys, 4.5% compared with 0.5%, respectively.9 Once adulthood is reached, bacteriuria increases in young, nonpregnant women (range, 1%–3%), yet remains low in men (up to 0.1%).10 Symptomatic UTI affects 30% of women between 20 and 40 years of age, which represents a prevalence that is 30 times greater than that of men in the same age group. The lifetime risk of UTIs in women is as high as 50% based on symptomatic reporting.11
The etiology of UTIs has remained relatively unchanged over the past several decades. KEY CONCEPT UTIs are either uncomplicated or complicated. There is a lack of consensus regarding the definition of what makes a UTI complicated (specifically in postmenopausal women or patients with diabetes mellitus), but in general, a complicated UTI refers to a structural or functional abnormality of the urinary tract.1 Patients with complicated UTIs are typically given longer treatment durations than those patients with uncomplicated infections. Those with complicated UTIs by definition are also prone to more frequent infections. It is important to note that an upper UTI does not necessarily imply complicated UTI, nor does lower UTI imply uncomplicated UTI.
There are three potential ways for bacteria to enter into the urinary tract and cause infection: the ascending, hematogenous, and lymphatic pathways.