Description

• Urinary tract infection (UTI) is the presence of pathogenic microorganisms in the urinary tract causing symptoms (see “History”).
• Uncomplicated UTI: UTI in patients with an anatomically normal urinary tract with no obstruction, no predisposing risk factors and symptoms confined to the lower urinary tract
• Complicated UTI: UTI in the presence of anatomical or functional abnormality, immunocompromised host, or a multidrug resistant organism (see “Risk Factors”)
• Recurrent UTI: symptomatic; occurs following complete treatment and resolution of documented infection; ≥2 culture-proven infections in 6 months, or ≥3 in 12 months.
• Asymptomatic bacteriuria (ASB): presence of bacteria in urine with no symptoms
• Synonym(s): cystitis

Epidemiology

UTIs are highly prevalent among women (1).

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 the initiation and propagation of UTIs.
• Most UTIs are caused by bacteria originating from bowel flora:
  • Escherichia coli is the causative organism in 75–95% of cases of uncomplicated UTIs.
  • Less common: Staphylococcus saprophyticus, Klebsiella pneumoniae, Proteus mirabilis

Risk Factors

• Biologic:
  • Urinary stasis/obstruction: pelvic organ prolapse, bladder diverticula, neurogenic bladder, voiding dysfunction, urethral stricture, anatomic anomalies of the urinary tract
  • Urinary calculi
  • Immunosuppression: diabetes, HIV, malignancy, malnutrition
• Behavioral practices that promote colonization:
  • Sexual intercourse
  • Use of spermicides or antimicrobials
  • Poor hygiene

General Prevention

• Resolve urinary obstruction/stasis
• Adequate hydration
• Women with frequent/intercourse-related UTI should empty bladder immediately before and after intercourse.
• Avoid feminine hygiene sprays, diaphragms, spermicidal agents, and douches.
• Vaginal estrogen in postmenopausal women may help prevent recurrent UTI (2)[C].

Commonly Associated Conditions

See “Risk Factors.”Geriatric Considerations

• Elderly patients due to underlying urinary tract abnormality or voiding dysfunction, or other comorbidities:
  • Poor hygiene, urinary/fecal incontinence, pelvic organ prolapse
  • Low estrogen levels increase vaginal pH and alter microbial flora, leading to increased colonization with pathogenic organisms.
• May present with atypical symptoms such as altered mental status or urinary incontinence
• Treatment of ASB does not improve outcomes and should be avoided.

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