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Chapter 28. Urinary Tract Infections

Eugene Kreys

Pathophysiology

  • Epidemiology: most common bacterial infection; 50–80% of women ≥1 in lifetime
  • Pathogenesis: majority via ascending pathway (infectious organism ascends urethra); hematogenous spread (from bloodstream), very rare
  • Approach to characterization:
    • Healthcare associated (≥48h after admission) vs community acquired
    • Chronic (persistent [>2wk] or recurrent UTI [≥2 episodes in 6mo]) vs acute
    • Site: cystitis (bladder, urethra) vs pyelonephritis (kidney) vs prostatitis (prostate)
    • Uncomplicated → infection in otherwise healthy nonpregnant adult
    • Complicated → ↑ risk of treatment failure → ♂ (vast majority ♂ UTIs considered complicated → infants, elderly, urologic abnormalities), pregnant, unusual (or highly resistant) pathogen, DM, renal transplant, immunosuppression, history of pyelonephritis within past year, functional or structural abnormality

Table 28-1 Abnormalities Associated with Complicated UTI
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Table 28-1 Abnormalities Associated with Complicated UTI

Obstruction

Prostatic hyperplasia

Urolithiasis

Ureteric stricture

Tumors

Congenital abnormality

Instrumentation

Urethral catheter

Ureteric stent

Urological procedure

Functional

Neurogenic bladder

Vesicoureteral reflux

Metabolic/hormonal

Diabetes

Pregnancy

Immunocompromised state

Renal transplant

Neutropenia

HIV

Diagnosis & Evaluation

Table 28-2 Common Signs & Symptoms
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Table 28-2 Common Signs & Symptoms

Signs & Symptoms

Comments

Severe dysuria: sharp, burning sensation, often worse toward end or immediately after micturition

Considered classic symptoms of UTI

May be due to urinary obstruction, vaginitis (Candida spp., Gardnerella vaginalis, Trichomonas vaginalis), or urethritis as result of STD (Neisseria gonorrhoeae, Chlamydia trachomatis, herpes simplex virus, Mycoplasma genitalium, Trichomonas vaginalis)

Increased frequency: may include nocturia

Urgency: sudden need to void; may be accompanied by:

   Urge incontinence: leakage of urine due to strong, sudden urge to urinate

   Strangury: painful passing of only small urine volume with straining despite a strong urge to urinate, usually with a residual feeling of incomplete emptying

Malodorous urine

May be a result of vaginitis or STD

Cloudy urine: may contain pus

Macroscopic hematuria: red/bloody urine

May be a sign of serious illness, such as cancer along the urinary tract or kidney/bladder stones (esp. if no other UTI symptoms)

Suprapubic, back (esp. CVA), flank, rectal, or perineal aching/pain/tenderness

Flank pain & CVA tenderness suggest pyelonephritis

Lower back, rectal, or perineal pain in ♂ may be result of prostatitis

Symptoms may suggest other intra-abdominal or pelvic process

Nonspecific malaise, aching, nausea, fatigue, fever, cold sweats, altered mental state

Suggests pyelonephritis; may be a result of other infectious processes AMS often only symptom in elderly

Fever often only symptom in catheterized patients

Urine collection: midstream clean-catch recommended; other collection methods: indwelling catheter, ileal conduit, straight catheterization, suprapubic catheter, cystoscopy (do not use specimen from 24h urine collection)

  • Urine culture: order with urinalysis (UA) or as follow up to abnormal UA; recommended for complicated UTI, healthcare-associated UTI, suspected pyelonephritis, relapse or persistent infection after initial therapy
  • + urine culture: high colony count (≥100,000CFU/mL = significant bacteriuria) of single bacterial type → probable infection; symptoms ...

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