Treatment of Asymptomatic Bacteriuria with E. coli and Enterococcus spp.
Asymptomatic bacteriuria with E. coli and Enterococcus spp. at a bacterial load of 50,000-100,000 CFU/mL should NOT be treated with antibiotics unless the patient belongs to specific high-risk groups.
Understanding Asymptomatic Bacteriuria
Asymptomatic bacteriuria refers to the presence of bacteria in the urine without clinical symptoms of urinary tract infection. The bacterial load of 50,000-100,000 CFU/mL is considered significant but does not automatically warrant treatment.
When NOT to Treat
- General population with no symptoms
- Elderly patients without specific risk factors
- Patients with indwelling catheters without symptoms
- Diabetic patients without symptoms
The European Association of Urology (EAU) guidelines clearly indicate that treating asymptomatic bacteriuria increases the risk of symptomatic infection, bacterial resistance, and healthcare costs 1.
When to Consider Treatment
Treatment should be limited to specific populations:
- Pregnant women
- Patients undergoing urological procedures with mucosal bleeding
- Immunocompromised patients with severe neutropenia
- Patients with renal transplants
Rationale for Non-Treatment
Antimicrobial Stewardship: Unnecessary antibiotic use promotes resistance development, particularly concerning with E. coli and Enterococcus species 2.
Natural Clearance: Many cases of asymptomatic bacteriuria resolve spontaneously without intervention.
Potential Harm: Treatment may disrupt normal flora and select for resistant organisms, potentially leading to more difficult-to-treat infections in the future 1.
Mixed Flora Considerations: The presence of both E. coli and Enterococcus spp. suggests possible contamination or colonization rather than true infection, especially in the absence of symptoms.
Management Approach
For Symptomatic Infections Only
If the patient develops symptoms (dysuria, frequency, urgency, suprapubic pain), treatment should be initiated based on culture results:
For uncomplicated UTIs with E. coli:
- Nitrofurantoin 100 mg PO every 6 hours for 5 days
- Fosfomycin 3 g PO single dose
- Trimethoprim-sulfamethoxazole 160/800 mg PO twice daily for 3-5 days (if local resistance <20%) 3
For complicated UTIs with both organisms:
Special Considerations for Enterococcus
Enterococcus species have intrinsic resistance to many antibiotics:
- Nitrofurantoin remains effective against most E. faecalis strains 5
- Fosfomycin shows good activity against enterococci 6
- Vancomycin-resistant Enterococcus (VRE) may require specialized treatment with linezolid or daptomycin 2
Monitoring Recommendations
- If the patient is asymptomatic, no follow-up cultures are necessary
- If symptoms develop, obtain cultures before initiating therapy
- For patients with recurrent UTIs, consider urological evaluation for structural abnormalities
Common Pitfalls to Avoid
Overtreating Asymptomatic Bacteriuria: This leads to unnecessary antibiotic exposure and promotes resistance.
Ignoring Local Resistance Patterns: Local antibiograms should guide empiric therapy when treatment is indicated.
Inadequate Treatment Duration: When treatment is indicated, ensure appropriate duration based on infection classification (uncomplicated vs. complicated).
Failure to Consider Host Factors: Immunocompromised status, pregnancy, and planned urological procedures may warrant treatment of otherwise asymptomatic bacteriuria.
In conclusion, the presence of E. coli and Enterococcus spp. in urine with a bacterial load of 50,000-100,000 CFU/mL without symptoms should not be treated with antibiotics in most patient populations. Treatment should be reserved for specific high-risk groups or when symptoms develop.