Adult Guidance
Upper Urinary Tract Infection

Upper Urinary Tract Infection

Note

This guidance focuses on community-acquired pyelonephritis in patients with no catheter

Definition

Infection of the kidneys (pyelonephritis) in which microorganisms ascend the urinary tract via the urethra, bladder, ureters or reach the kidneys through the bloodstream

Classification based on complexity:

  • Uncomplicated: Urinary tract infections (UTI) in individuals with no risk factors for complicated UTI
  • Complicated: UTI in individuals with structural anomalies of the urinary tract (e.g. kidney stones, anatomical anomalies) or who are immunocompromised and in pregnant women are generally considered complicated (or at risk of complications). UTI in patients with urinary catheters or stents are also considered complicated (not discussed here)

Diagnosis

  • Flank pain, costovertebral angle tenderness, nausea and vomiting, fever and signs of systemic illness +/- symptoms of cystitis
  • Severity varies from mild disease (most cases) that can be managed with oral treatment (no nausea/vomiting, low-grade fever) to severe cases requiring intravenous treatment and hospital admission

All cases (if upper UTI is suspected clinically):

  • Urine culture: Ideally before starting antibiotic treatment
    • The test is considered positive when bacteria are above a certain minimum cut-off that can vary between laboratories
    • A positive urine culture is not always a sign of urinary tract infection or an indication for antibiotic treatment (and urine can also become contaminated during sampling)

Additionally in severe cases:

  • Blood cultures: Ideally before starting antibiotic treatment

All cases (if upper UTI is suspected clinically):

  • Urinalysis (dipstick or microscopy) to detect bacteriuria and/or indirect signs of infection (positive leucocyte esterase and nitrites)

Additionally in severe cases:

  • White blood cell count, C-reactive protein and/or procalcitonin
  • If sepsis is suspected consider additional laboratory tests (see sepsis guidance below)

Routine imaging is not necessary but can be considered if urine flow is blocked or an abscess is suspected

Microbiology

Treatment

  • Patients with upper urinary tract infection are generally symptomatic
  • Patients with a positive urine test but no UTI symptoms usually do not require treatment (exceptions exist, e.g. pregnant women or if invasive urologic procedure is scheduled, for whom pre-emptive antibiotic therapy may be indicated)

Important:

  • Simplify empiric treatment to a more narrow-spectrum antibiotic based on culture results or rapid clinical improvement if culture results unavailable
  • Step down to oral treatment is based on improvement of symptoms, signs of infection and the ability to take oral antibiotics
  • Clinical improvement is usually evident within 48-72 hours of starting treatment; if signs and symptoms persist, consider and investigate a possible complication (e.g. abscess) and review the results of the urine culture to verify that the pathogen is susceptible to the antibiotic used

Additional Information