Oral Cephalosporin Dosing for Uncomplicated UTI
For uncomplicated urinary tract infections, cefixime 400 mg once daily is the recommended oral cephalosporin regimen, which may be given as a single daily dose or divided as 200 mg twice daily for better gastrointestinal tolerance. 1
Specific Oral Cephalosporin Options and Dosing
Cefixime
- Dosage for adults: 400 mg daily (can be given as single dose or divided)
- Duration: 7 days for uncomplicated UTI
- Administration: Can be taken without regard to food
- Renal adjustment:
- CrCl ≥60 mL/min: Normal dose
- CrCl 21-59 mL/min: 200 mg daily
- CrCl ≤20 mL/min: 100 mg daily 1
Cefuroxime Axetil
- Dosage for adults: 250-500 mg twice daily
- Duration: 7-10 days
- Administration: Take with food to enhance absorption 2
Cefaclor
- Dosage for adults: 250-500 mg three times daily
- Duration: 7 days for uncomplicated UTI 3
Patient-Specific Considerations
Renal Function Assessment
- Renal function assessment is critical before selecting and dosing cephalosporins
- Dose adjustments are necessary for patients with impaired renal function 4, 1
Antimicrobial Susceptibility
- Urine culture with antimicrobial susceptibility testing is essential to confirm infection and guide antibiotic therapy
- Cephalosporins are generally effective against common UTI pathogens like E. coli and Klebsiella 4
Treatment Duration
- 7 days is sufficient for most uncomplicated UTIs showing clinical improvement 4
- Clinical improvement should be evident within 24-48 hours 4
Monitoring and Follow-up
- Monitor for clinical improvement within 48-72 hours
- Consider repeat urine culture if symptoms persist 4
- Adjust antibiotics based on susceptibility testing if necessary
Special Populations
Pediatric Dosing for Cefixime
- Recommended dose: 8 mg/kg/day of suspension
- Can be administered as single daily dose or divided (4 mg/kg every 12 hours)
- For children >45 kg or >12 years: Use adult dose 1
Elderly Patients
- Consider age-related decline in renal function
- May require dose adjustment based on creatinine clearance 1
Common Pitfalls and Caveats
- Cephalosporins may not be effective against Enterococcus species, which are common UTI pathogens
- For patients with sulfa allergies, cephalosporins may be a good alternative, but cross-reactivity can occur in patients with severe penicillin allergies
- Gastrointestinal side effects are more common with once-daily dosing of cefixime; dividing the dose (200 mg twice daily) may improve tolerance 5
- Cephalosporins with significant biliary excretion (like ceftriaxone) may not achieve adequate urinary concentrations in patients with significant renal dysfunction 6
Alternative Oral Options After IV Therapy
- When switching from IV to oral therapy after clinical improvement:
- Cephalosporins (as outlined above)
- Amoxicillin plus clavulanic acid
- Trimethoprim-sulfamethoxazole (based on susceptibility testing) 4