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SOURCE

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Source: Coyle EA, Prince RA. Urinary tract infections and prostatitis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146072433. Accessed March 28, 2017.

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DEFINITIONS

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  • Presence of microorganisms in urine that cannot be accounted for by contamination.

    • Lower tract infections include:

      • Cystitis (bladder)

      • Urethritis (urethra)

      • Prostatitis (prostate gland)

      • Epididymitis.

    • Upper tract infections involve kidney and referred to as pyelonephritis.

    • Uncomplicated urinary tract infections (UTIs) are not associated with structural or neurologic abnormalities.

    • Complicated UTIs result of predisposing lesion of urinary tract:

      • Congenital abnormality or distortion of urinary tract.

      • Stone.

      • Indwelling catheter.

      • Prostatic hypertrophy.

      • Obstruction.

      • Neurologic deficit.

    • Recurrent UTIs: ≥3 UTIs occurring within 1 year.

      • Characterized by multiple symptomatic episodes with asymptomatic periods in between.

      • Due to reinfection with different organism or relapse caused by same initial organism.

    • Asymptomatic bacteriuria: significant bacteriuria (>105 bacteria/mL of urine) in absence of symptoms.

      • Common in persons 65 years of age and older.

    • Symptomatic abacteriuria: symptoms of frequency and dysuria in absence of significant bacteriuria.

      • Commonly associated with Chlamydia infections.

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ETIOLOGY

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  • Usually caused by single bacterial organism that originates from bowel flora of host.

    • Uncomplicated UTIs most commonly caused by Escherichia coli.

    • Complicated UTIs caused by variety of organisms generally more resistant.

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PATHOPHYSIOLOGY

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  • Acquired via 3 possible pathways:

    • Ascending.

      • Primary UTI acquisition route in females.

        • Urethra colonized from perirectal area, which then enters bladder and can ascend ureters to kidney.

    • Hematogenous (descending)

      • Result of dissemination of organisms from distant primary infection.

      • Uncommon.

    • Lymphatic.

      • Insignificant role.

  • Development of infection depends on:

    • Size of inoculum.

    • Virulence of microorganism.

      • Bacteria adhere to urinary epithelial cells by fimbriae, resulting in colonization of urinary tract, bladder infections, and pyelonephritis.

      • Additional virulence factors: hemolysin and aerobactin.

    • Host defense mechanisms.

      • Normal urinary tract resistant to invasion by bacteria and efficient in rapidly eliminating microorganisms that reach bladder.

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EPIDEMIOLOGY

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  • Prevalence of UTIs varies with age and gender.

    • Overall incidence increases substantially in persons older than 65 years, with majority of infections being asymptomatic.

    • More common in females because of anatomic differences in location and length of urethra, which supports ascending route of infection.

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PREVENTION

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  • Voiding after intercourse may help prevent recurrent infections in women.

  • Limit length of time of catheterization.

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RISK FACTORS

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  • Age.

  • Underlying structural abnormalities of urinary tract.

    • Obstruction from bladder hypertrophy.

  • Poor bladder emptying resulting in residual urine volumes.

    • Prostatic hypertrophy.

    • Tumors.

    • Anticholinergic drugs.

    • Neuromuscular disease (including strokes)

  • Resident of nursing home.

  • Frequent hospitalizations.

  • Fecal incontinence.

  • Urinary catheterization.

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CLINICAL PRESENTATION

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  • Elderly patients frequently do not experience specific urinary symptoms, but will present with:

    • Altered mental status.

    • Change in eating habits.

    • Gastrointestinal (GI) symptoms.

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