What is the recommended treatment for a patient with Aerococcus viridans (A. viridans) bacteriuria, with a colony count of 10,000-49,000 colony-forming units per milliliter (cfu/ml)?

Management of Aerococcus viridans in Urine Culture (10,000-49,000 CFU/mL)

For asymptomatic Aerococcus viridans bacteriuria with colony counts of 10,000-49,000 CFU/mL, treatment is not recommended as this represents asymptomatic bacteriuria which should not be treated in non-pregnant adults.

Assessment of Clinical Significance

The finding of Aerococcus viridans in urine culture at 10,000-49,000 CFU/mL requires careful interpretation:

1. Determine if patient is symptomatic or asymptomatic:

   • Symptomatic: Presence of dysuria, frequency, urgency, suprapubic pain
   • Asymptomatic: No urinary symptoms

2. Assess patient risk factors:

   • Pregnancy status
   • Presence of urologic abnormalities
   • Immunocompromised status
   • Planned urologic procedures

Management Algorithm

For Asymptomatic Patients:

• Non-pregnant adults: No treatment recommended 1
• Pregnant women: Treatment recommended regardless of colony count 1
• Pre-urologic procedure: Treatment recommended only if procedure involves mucosal trauma 1

For Symptomatic Patients:

Treatment is indicated based on susceptibility testing. Options include:

• First-line options:

  • Penicillin or ampicillin (if susceptible) 2
  • Nitrofurantoin 100mg twice daily for 5-7 days 3, 4
  • Trimethoprim-sulfamethoxazole (if susceptible) 5

• For resistant strains:

  • Vancomycin 6, 5
  • Levofloxacin 7

Rationale for Non-Treatment in Asymptomatic Cases

The Infectious Diseases Society of America (IDSA) guidelines strongly recommend against screening for or treating asymptomatic bacteriuria in non-pregnant adults 1. This recommendation is based on:

1. Lack of evidence for clinical benefit
2. Risk of promoting antimicrobial resistance
3. Risk of adverse drug reactions
4. Potential for Clostridioides difficile infection

Special Considerations

Pregnancy

If the patient is pregnant, treatment is recommended regardless of symptoms or colony count due to increased risk of pyelonephritis and adverse pregnancy outcomes 1.

Urologic Procedures

For patients undergoing invasive urologic procedures with mucosal trauma, pre-procedure screening and treatment is recommended 1.

Immunocompromised Patients

A. viridans can cause serious infections including bacteremia and endocarditis in immunocompromised patients 4, 6. Lower thresholds for treatment may be appropriate in these populations.

Common Pitfalls

1. Overtreatment of asymptomatic bacteriuria: Treating asymptomatic bacteriuria in non-pregnant adults leads to unnecessary antibiotic use and potential harm 1.

2. Misidentification: A. viridans can be misidentified as streptococci or dismissed as a contaminant 6. Proper identification methods like MALDI-TOF are recommended.

3. Inadequate susceptibility testing: A. viridans can show resistance to multiple antibiotics, including penicillins 5. Treatment should be guided by susceptibility results.

4. Failure to recognize true infection: In symptomatic patients or those with risk factors, A. viridans should be considered a potential pathogen rather than a contaminant 6, 7.