Pyelonephritis

Basics

Description

  • Inflammation of the renal pelvis and kidney
  • Severity of illness can vary from mild symptoms to septic shock
  • Frequently complication of a lower UTI by bacterial ascension into the upper urinary tract
  • Primarily a clinical diagnosis
  • Incidence lower in males in every age group
  • >50% lifetime incidence in females in some studies
  • Male/female ratio:
    • 1:10 in first years of life
    • 1:5 in children
    • 1:50 in reproductive years
    • 1:1 in fifth decade and later
  • Bilateral infection in up to 25% of cases, hence no lateralizing signs (in some studies)

Etiology

  • Bacteriology:
    • Escherichia coli (>90% in young women)
    • Uropathogens:
      • Klebsiella species
      • Citrobacter species
      • Enterobacter species
    • Others:
      • Staphylococcus saprophyticus 5–15%
      • Proteus mirabilis
      • Serratia species
      • Pseudomonas species
      • Staphylococcus aureus (increasing)
      • Candida species (rare)
  • Predisposing factors (consider complicated infections):
    • Recent instrumentation:
      • Catheterization
      • Cystoscopy
    • Urinary retention:
      • Mechanical (see Obstruction)
      • Medications (e.g., anticholinergics)
      • Other infections (e.g., herpes simplex)
    • Urinary obstruction:
      • Stricture
      • Renal calculi
      • Prostatic hypertrophy
    • Anatomic abnormalities:
      • Hypospadias
      • Ureteral ectopia
      • Bifid ureter
      • Renal scarring
      • Ureterovesicular reflux (UVR)
      • Posterior urethral valves
    • Neurologic conditions:
      • Neurogenic bladder
      • Spinal cord injury
    • Abnormal urodynamics
    • Previous UTIs (in childhood, >3 in last year)
    • Recent pyelonephritis (within 1 yr)
    • Diabetes mellitus
    • Immunosuppression
    • Pregnancy
    • Advanced age (>65 yr of age)

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