Urinary Tract Infections: Contemporary Management
David D. Rahn, MD, FACOG Published: 11/12/2008
Abstract and Introduction
Urinary tract infections (UTIs) are an increasingly prevalent problem for women. The diagnosis and management of uncomplicated acute cystitis is relatively straightforward, while complicated and recurrent infections require morespecialized assessment and treatment. This article will review the current management of UTIs.
Infections of the upper and lower urinary tract account for more than 6 million office visits per year in the U.S., costing more than $2.5 billion annually (Griebling, 2005; Karram & Siddighi, 2008; Na tional Center for Health Statistics, 1977). Since 50% to 60% of women report at least oneurinary tract infection (UTI) in their lifetime, UTIs have become a common condition diagnosed and treated by gynecologists, urologists, and other health care providers for women (Foxman, 2002). This article will review the epidemiology of UTIs, the pathophysiology of this disease, the appropriate clinical and laboratory investigation, current treatment recommendations and algorithms, and the managementof UTIs in different clinical scenarios, including catheter-associated infections, infection during pregnancy, and acute pyelonephritis.
Definitions and Epidemiology
Cystitis refers to any inflammatory condition of the bladder. This definition may simply be a clinical diagnosis in the setting of irritative voiding symptoms and dysuria. When infectious in etiology, "cystitis" will often referto a bacteriologic finding from a urine culture, but cystitis may also be based on histologic or cystoscopic findings. Non-bacterial cystitis may occur after radiation exposure or in a disease known as interstitial cystitis, which by definition, has sterile urine (Karram & Siddighi, 2008). Complicated infections refer to those which occur concomitant with the conditions listed in Table 1 , such asUTIs in men, patients with diabetes mellitus, women who are pregnant, relapsing or recurrent infections, hospital-acquired infection, or UTIs commensurate with in dwelling catheters or recent urinary tract instrumentation. UTIs not fitting into one of these scenarios are commonplace and are considered "uncomplicated" (Johnson & Stamm, 1987).
Table 1. "Complicated" Urinary Tract InfectionsOther definitions relevant to the topic of UTI include urethritis, trigonitis, bacteriuria, and urethral syndrome. Urethritis indicates inflammation of the urethra; in women, this is clinically indistinguishable from cystitis. Trigonitis refers to a localized hyperemia of the bladder trigone. Bacteriuria denotes the presence of bacteria in the urine. A UTI may be diagnosed when as few as 102 colonyforming units of bacteria per milliliter (cfu/mL) are found in a symptomatic patient. Asymptomatic bacteriuria refers to greater than 105 cfu/mL in a patient without complaints consistent with a UTI (Norden & Kass, 1968; Stamm et al., 1982). Finally, "urethral syndrome" is a term that has been ascribed to patients with urinary frequency, urgency, dysuria, suprapubic discomfort, voidingdifficulties, and pyuria (white blood cells in the urine) but in the absence of organic pathology (for example, negative urine cultures) (Maskell, 1974; Maskell, Pead, & Allen, 1979). UTIs are mostly found in women, occurring in an 8:1 ratio in women to men (Cox, Lacy, & Hinman, 1968). Aside from being common in the community, 2% of hospitalized patients acquire UTIs, accounting for more than 500,000nosocomial infections per year (Mayer, 1980; Turck & Stamm 1981). There are at least 100,000 annual hospitalizations for renal infections, which are usually the result of ascending infection from the lower urinary tract. Beginning at about 1 year of age, there is only about a 1% infection rate until puberty. Bacteriuria is found in 2% to 3% of women 15 to 24 years of age, 20% in women 65 to 80 years,...