Do we treat an asymptomatic patient with a urinalysis (UA) showing leukocyte esterase 2+ and a urine culture positive for Methicillin-resistant Staphylococcus aureus (MRSA)?

Management of Asymptomatic Bacteriuria with MRSA in Urine

Asymptomatic bacteriuria with MRSA in urine should not be treated with antibiotics, regardless of the presence of leukocyte esterase on urinalysis. 1

Diagnostic Considerations

• The presence of leukocyte esterase 2+ on urinalysis indicates pyuria (white blood cells in urine)
• MRSA-positive urine culture indicates bacteriuria
• Without symptoms, this combination represents asymptomatic bacteriuria, not a urinary tract infection

Evidence-Based Rationale

Guidelines on Asymptomatic Bacteriuria

• Multiple clinical guidelines explicitly recommend against treating asymptomatic bacteriuria:
  • AUA/SUFU guideline states: "Clinicians should not treat asymptomatic bacteriuria in patients" 1
  • IDSA guideline emphasizes: "Urinalysis and urine cultures should not be performed for asymptomatic residents" 1
  • The AUA/SUFU guideline on neurogenic lower urinary tract dysfunction states: "Clinicians should not treat asymptomatic bacteriuria in patients with NLUTD" 1

Risks of Unnecessary Treatment

• Treating asymptomatic bacteriuria leads to:
  • Development of antibiotic resistance 1
  • Early recurrence of bacteriuria with more resistant strains 1
  • Unnecessary adverse effects from antibiotics
  • Increased healthcare costs

When to Consider Treatment

Treatment of asymptomatic bacteriuria is only indicated in:

• Pregnant women 2
• Patients prior to urologic procedures involving mucosal bleeding 1

Surveillance Testing Considerations

• Guidelines also recommend against routine surveillance urine cultures in asymptomatic patients 1
• The AUA/SUFU guideline states: "Clinicians should omit surveillance urine testing, including urine culture, in asymptomatic patients" 1

Clinical Approach

1. Verify true absence of symptoms

   • Ensure patient truly has no urinary symptoms (dysuria, frequency, urgency, suprapubic pain)
   • Rule out fever, flank pain, or other systemic symptoms that would suggest pyelonephritis

2. Interpret laboratory findings properly

   • Leukocyte esterase has high sensitivity (84%) but lower specificity (78%) for inflammation 2
   • Positive urine culture with MRSA without symptoms represents colonization, not infection

3. Document decision

   • Clearly document the decision not to treat asymptomatic bacteriuria
   • Note that treatment is not indicated based on current guidelines

Common Pitfalls to Avoid

• Overtreating based on laboratory findings alone: The presence of bacteria and leukocytes in urine without symptoms does not warrant antibiotic treatment
• Misinterpreting non-specific symptoms: Vague symptoms unrelated to the urinary tract should not trigger treatment of bacteriuria
• Defensive medicine: Treating "just to be safe" leads to antibiotic resistance and patient harm
• Failing to distinguish colonization from infection: MRSA can colonize the urinary tract without causing infection, particularly in catheterized patients

Special Considerations for MRSA

While MRSA is a concerning pathogen, the principles of asymptomatic bacteriuria management remain the same regardless of the organism. The presence of MRSA alone without symptoms does not justify antibiotic treatment 3, 4.