Description

• Urinary tract infection (UTI) is the presence of pathogenic microorganisms within the urinary tract and associated symptoms (dysuria, urinary urgency/frequency, hematuria, new or worsening incontinence).
• Uncomplicated UTI: infection in patients with an unobstructed and anatomically normal urinary tract, with no predisposing risk factors, and whose symptoms are confined to the lower urinary tract
• Complicated UTI: infection of the urinary tract in the presence of an anatomic or functional abnormality, immunocompromised host, or presence of a multi-drug resistant organism (See “Risk Factors.”)
• Recurrent UTI: symptomatic UTI that occurs following complete treatment and resolution of documented infection; two or more culture-proven infections in 6 months or three or more in 12 months; affects 20–40% of women with prior cystitis episodes (1)
• Asymptomatic bacteriuria: presence of bacteria in urine without reports of associated symptoms
• Synonym(s): cystitis

Epidemiology

UTI among women is an extremely common occurrence.

Incidence

• Accounts for 10.5 million office visits and 2 to 3 million emergency room visits; contributes to >100,000 hospital admissions each year with a cost of >$2.6 billion annually
• Primarily affects young adults and older adults; predominantly female > male

Prevalence

• Up to 60% of females have at least one UTI in their lifetime, and 11% report having at least one per year.
• 1/4 of women with uncomplicated UTI experience a second UTI within 6 months and half at some time during their lifetime.

Etiology and Pathophysiology

• Ascension of bacteria into the bladder via the urethra is the most common etiology.
• Pathogenic organisms possess adherence factors (pili or fimbriae) and toxins that allow initiation and propagation of genitourinary infections.
• Most UTIs are caused by bacteria originating from bowel flora:
  • Escherichia coli is the causative organism in 80–85% of cases of uncomplicated cystitis.
  • Staphylococcus saprophyticus accounts for 10–15% of infections.
  • Klebsiella pneumoniae and Proteus mirabilis each account for approximately 4%.

Genetics
Women with human leukocyte antigen 3 (HLA-3) and nonsecretor Lewis antigen have an increased bacterial adherence, which may lead to an increased risk in UTI.

Risk Factors

• Biologic:
  • Urinary stasis/obstruction: pelvic organ prolapse, bladder diverticula, neurogenic bladder, voiding dysfunction, urethral stricture, anatomic anomalies of the lower urinary tract
  • Urinary calculi
  • Immunosuppression: diabetes, HIV, steroid use, malignancy, malnutrition
• Behavioral practices that promote colonization: sexual intercourse, spermicide, estrogen depletion, antimicrobial use, poor hygiene

General Prevention

• Mitigate urinary obstruction or stasis.
• Adequate hydration
• Women with frequent or intercourse-related UTI should empty bladder immediately before and following intercourse.
• Avoid feminine hygiene sprays, diaphragms, spermicidal agents, and douches.
• Wipe urethra from front to back.
• Vaginal estrogen in postmenopausal women may aid in preventing recurrent UTI.

Commonly Associated Conditions

See “Risk Factors.”

Geriatric Considerations

• Elderly patients are more likely to have underlying urinary tract abnormality or voiding dysfunction.
  • Poor perineal hygiene, urinary or fecal incontinence, and pelvic organ prolapse are common risk factors.
  • Decreased estrogen levels increase vaginal pH and alter microbial flora, leading to increased colonization.
• May present with atypical symptoms such as altered mental status or urinary incontinence
• Treatment of asymptomatic bacteriuria does not improve outcomes and should be avoided due to associated morbidity.

Pediatric Considerations
Bowel bladder dysfunction or congenital urinary tract abnormalities such as vesicoureteral reflux (VUR) or duplicated collecting system are risk factors.