Treatment of Multiple E. coli Urinary Tract Infections
For uncomplicated E. coli UTI, use nitrofurantoin 100mg PO four times daily for 5 days, fosfomycin 3g PO single dose, or trimethoprim-sulfamethoxazole 160/800mg twice daily for 3 days as first-line therapy; avoid fluoroquinolones unless local resistance patterns and patient factors necessitate their use. 1
Initial Assessment and Culture Requirements
- Obtain urine culture with susceptibility testing before initiating therapy in complicated cases, recurrent infections, or when the catheter has been removed 1
- Remove any indwelling urinary catheters immediately if present, as catheterization is a major risk factor for E. coli UTIs 2
- Check local antibiograms before selecting empiric therapy, as resistance patterns vary significantly by region 1
First-Line Treatment for Uncomplicated UTI
Preferred oral agents:
- Nitrofurantoin 100mg PO four times daily for 5 days 1
- Fosfomycin 3g PO single dose 1
- Trimethoprim-sulfamethoxazole 160/800mg twice daily for 3 days (only if local resistance <20%) 1
Critical caveat: Avoid fluoroquinolones (ciprofloxacin, levofloxacin) as first-line therapy due to increasing resistance rates, FDA warnings regarding serious adverse effects including tendon rupture and peripheral neuropathy, and collateral damage to the microbiome 1
Treatment for Complicated UTI or Pyelonephritis
For mild-to-moderate complicated UTI:
- Ciprofloxacin 500mg PO twice daily or levofloxacin 750mg PO daily for 7-10 days (if susceptible and local resistance <10%) 1, 3
- Duration: 7-10 days for complicated UTI, 10-14 days for pyelonephritis 2
For severe complicated UTI or suspected pyelonephritis requiring IV therapy:
- Ceftriaxone 2g IV every 24 hours 1
- Cefotaxime 2g IV every 8 hours 1
- Levofloxacin 750mg IV daily for 7-10 days (covers both E. coli and potential polymicrobial infections) 2, 3
Management of Resistant E. coli
For extended-spectrum beta-lactamase (ESBL)-producing E. coli:
- Non-severe infections: Amoxicillin-clavulanate or piperacillin-tazobactam 1
- Severe infections: Ertapenem 1g IV every 24 hours 1
For carbapenem-resistant E. coli (CRE):
- Ceftazidime-avibactam 2.5g IV every 8 hours for 5-7 days 4, 1
- Meropenem-vaborbactam 4g IV every 8 hours for 5-7 days 4
- Imipenem-cilastatin-relebactam 1.25g IV every 6 hours for 5-7 days 4
- Plazomicin 15mg/kg IV every 12 hours for complicated UTI 4
- Single-dose aminoglycoside (gentamicin 5-7mg/kg IV or amikacin 15mg/kg IV) for simple cystitis due to CRE 4
Special Considerations for Recurrent Infections
When treating "multiple" E. coli UTIs (recurrent infections):
- Distinguish between relapse (same strain within 2 weeks) versus reinfection (different strain or >2 weeks later) through culture comparison if available 1
- For relapse: Consider longer treatment duration (10-14 days) and investigate for structural abnormalities, retained foreign bodies, or inadequate source control 1
- For reinfection: Treat each episode according to susceptibility results; consider prophylaxis only after 2-3 infections within 6 months or 3+ infections within 12 months 1
Critical Pitfalls to Avoid
- Never treat asymptomatic bacteriuria (positive culture without symptoms) except in pregnancy or before urologic procedures, as this fosters resistance without clinical benefit 2, 1
- Avoid fluoroquinolone monotherapy if local resistance exceeds 10% or if the patient received fluoroquinolones within the past 3 months 2
- Do not use beta-lactams or fluoroquinolones unnecessarily due to collateral damage to the microbiome and promotion of resistance 1
- Avoid prolonged courses or unnecessarily broad-spectrum agents when narrow-spectrum options are effective based on susceptibility testing 1
- Do not ignore enterohemorrhagic E. coli (EHEC/STEC): Avoid antimotility drugs and antibiotics in suspected EHEC infections, as antibiotics may increase Shiga toxin production and risk of hemolytic uremic syndrome 4