What is the recommended treatment for an E. coli (Escherichia coli) urinary tract infection (UTI)?

Treatment for E. coli Urinary Tract Infection

For uncomplicated E. coli UTIs, first-line treatment is nitrofurantoin for 5 days, fosfomycin as a single 3g dose, or trimethoprim-sulfamethoxazole (only if local resistance is <20% and no recent use in past 3-6 months), with fluoroquinolones reserved as second-line options due to resistance concerns. 1, 2

Treatment Algorithm for Uncomplicated Cystitis

First-Line Options:

• Nitrofurantoin: 5-day course is recommended as a primary first-line agent 1, 2
• Fosfomycin tromethamine: Single 3g dose provides convenient single-dose therapy 1, 2
• Trimethoprim-sulfamethoxazole: Use only if local E. coli resistance is documented <20% AND the patient has not used this antibiotic in the previous 3-6 months 1, 2

Second-Line Options:

• Oral cephalosporins (cephalexin or cefixime) can be used when first-line agents are contraindicated 3
• Fluoroquinolones should be avoided as first-line therapy due to increasing resistance rates and adverse effect profiles 1, 2
• Amoxicillin-clavulanate is approved for UTIs caused by beta-lactamase-producing E. coli 4, 3

Critical Decision Point - Check Local Resistance Patterns:

• Always verify local antibiotic susceptibility patterns before selecting empiric therapy, as this significantly impacts treatment success 1, 2
• Avoid antibiotics with known local resistance rates >20% for empiric therapy 1, 2

Treatment for Complicated UTIs and Pyelonephritis

Oral Therapy for Pyelonephritis:

• Fluoroquinolone (ciprofloxacin 500mg twice daily for 7 days): Use only if local resistance <10% 2, 5
• Trimethoprim-sulfamethoxazole (160/800mg twice daily for 14 days): Use only if susceptibility is confirmed by culture 2
• Oral β-lactams: If using these agents, administer an initial IV dose of ceftriaxone 1g or aminoglycoside first 2

Parenteral Therapy for Hospitalized Patients:

• Initial IV options include fluoroquinolone, aminoglycoside (with or without ampicillin), extended-spectrum cephalosporin/penicillin, or carbapenem 2
• For complicated UTIs with systemic symptoms, use amoxicillin plus an aminoglycoside OR a second-generation cephalosporin plus an aminoglycoside 1
• Tailor therapy based on culture and susceptibility results once available 2

Treatment Duration:

• Uncomplicated cystitis: 5 days for nitrofurantoin, single dose for fosfomycin 1
• Complicated UTIs: 7-14 days depending on severity 1
• Pyelonephritis: 7-14 days depending on antibiotic choice and clinical response; consider 7 days when patient is hemodynamically stable and afebrile for at least 48 hours 1, 2

Special Populations and Resistant Organisms

Pediatric Patients:

• Oral options: Cefixime 8 mg/kg per day in 1 dose 2
• Parenteral options for febrile UTI: Ceftriaxone 75 mg/kg every 24h, cefotaxime 150 mg/kg per day divided every 6-8h, or gentamicin 7.5 mg/kg per day divided every 8h 2
• Treatment duration: 7-14 days 2
• Ciprofloxacin is indicated for pediatric inhalational anthrax but is not first-choice for UTI due to increased joint-related adverse events 5

Extended-Spectrum Beta-Lactamase (ESBL)-Producing E. coli:

• Oral options: Nitrofurantoin, fosfomycin, pivmecillinam, or amoxicillin-clavulanate 3
• Parenteral options: Piperacillin-tazobactam (for ESBL-E. coli only), carbapenems (including meropenem-vaborbactam, imipenem-cilastatin-relebactam), ceftazidime-avibactam, aminoglycosides, or cefiderocol 3
• For non-severe infections, aminoglycosides or quinolones may be considered for short treatments 6
• Ertapenem is preferred over meropenem/imipenem for bloodstream infections without septic shock due to single daily administration and antimicrobial stewardship considerations 6

Carbapenem-Resistant E. coli (CRE):

• Options include: Ceftazidime-avibactam 2.5g IV q8h, meropenem-vaborbactam 4g IV q8h, or imipenem-cilastatin-relebactam 1.25g IV q6h 1, 2, 3
• Single-dose aminoglycoside may be considered for simple cystitis due to CRE 2
• Additional options include colistin, fosfomycin, aztreonam combinations, and tigecycline 3

Recurrent UTIs:

• Consider prophylactic strategies, including post-coital antibiotics for premenopausal women with infection related to sexual activity 1, 2
• Do NOT treat asymptomatic bacteriuria in women with recurrent UTIs, as this fosters antimicrobial resistance and increases recurrence episodes 1, 2
• Obtain urine culture before treatment in patients with recurrent UTIs to guide therapy 1, 2

Common Pitfalls to Avoid

• Avoid fluoroquinolones as first-line therapy for uncomplicated UTIs due to increasing resistance and risk of serious adverse effects including tendon rupture, especially in elderly patients on corticosteroids 1, 2, 5
• Do not use inadequate treatment duration for pyelonephritis; ensure 7-14 days depending on antibiotic choice 1, 2
• Avoid empiric use of antibiotics with high local resistance (>20%) without culture confirmation 1, 2
• Do not fail to obtain pre-treatment urine culture in patients with recurrent UTIs, complicated UTIs, or risk factors for resistant organisms 1, 2
• Avoid treating asymptomatic bacteriuria as this promotes resistance without clinical benefit 1, 2
• Do not use trimethoprim-sulfamethoxazole if the patient has used it in the previous 3-6 months due to increased resistance risk 1, 2
• Limit carbapenem use if alternatives are available to preserve these agents for severe infections 6