Recommended IV Antibiotics for Severe Urinary Tract Infections
For severe urinary tract infections requiring hospitalization, the recommended initial intravenous antimicrobial regimens include fluoroquinolones (ciprofloxacin 400 mg twice daily or levofloxacin 750 mg daily), extended-spectrum cephalosporins (ceftriaxone 1-2 g daily or cefepime 1-2 g twice daily), or aminoglycosides with or without ampicillin. 1
First-line IV Antibiotic Options for Severe UTIs
Fluoroquinolones
- Ciprofloxacin 400 mg IV twice daily 1
- Levofloxacin 750 mg IV once daily 1
- Only use when local fluoroquinolone resistance is <10% 1
Extended-spectrum Cephalosporins
- Ceftriaxone 1-2 g IV once daily (higher dose recommended despite lower dose being studied) 1
- Cefepime 1-2 g IV twice daily (higher dose recommended despite lower dose being studied) 1, 2
- Cefotaxime 2 g IV three times daily 1
Aminoglycosides
- Gentamicin 5 mg/kg IV once daily 1, 3
- Amikacin 15 mg/kg IV once daily 1
- Note: Aminoglycoside monotherapy should only be used for urinary tract infections, not for systemic infections 3
Beta-lactam/Beta-lactamase Inhibitor Combinations
- Piperacillin/tazobactam 2.5-4.5 g IV three times daily 1
Treatment Duration and Transition to Oral Therapy
- Initial IV therapy should be continued until clinical improvement is observed 1
- For uncomplicated pyelonephritis, total treatment duration is typically 7 days 1
- For complicated UTIs, treatment duration should be 5-10 days, individualized based on clinical response 4
- Consider transitioning to oral therapy once clinical improvement occurs, with options including:
Special Considerations for Complicated UTIs
Multidrug-Resistant Organisms
- Carbapenems and novel broad-spectrum antimicrobials should only be used when culture results indicate multidrug-resistant organisms 1
- Options include:
- Imipenem/cilastatin 0.5 g IV three times daily 1
- Meropenem 1 g IV three times daily 1
- Ceftolozane/tazobactam 1.5 g IV three times daily 1, 3
- Ceftazidime/avibactam 2.5 g IV three times daily 1, 3
- Cefiderocol 2 g IV three times daily 1
- Meropenem-vaborbactam 2 g IV three times daily 1, 3
- Plazomicin 15 mg/kg IV once daily 1
Dosage Adjustments for Renal Impairment
- For cefepime in patients with creatinine clearance 30-60 mL/min: 2 g IV every 24 hours 2
- For cefepime in patients with creatinine clearance 11-29 mL/min: 1 g IV every 24 hours 2
- For cefepime in patients with creatinine clearance <11 mL/min: 500 mg IV every 24 hours 2
- For patients on hemodialysis receiving cefepime: 1 g on day 1, then 500 mg every 24 hours thereafter; administer after hemodialysis on dialysis days 2
Important Clinical Considerations
- Treatment should be tailored to local resistance patterns 1, 3
- Ensure adequate source control (relief of obstruction, removal of foreign bodies) for optimal outcomes 3
- For patients with bacteremia associated with complicated UTI, extend treatment duration to 7-14 days 3
- The microbial spectrum for complicated UTIs is broader than for uncomplicated UTIs, with common pathogens including E. coli, Proteus spp., Klebsiella spp., Pseudomonas spp., Serratia spp., and Enterococcus spp. 1
- Susceptibility testing should be performed when possible to adjust therapy accordingly 4, 5
Common Pitfalls to Avoid
- Using fluoroquinolones empirically in areas with resistance rates >10% 1
- Using aminoglycosides as monotherapy for systemic infections rather than just urinary tract infections 3
- Failing to adjust antibiotic dosages in patients with renal impairment 2
- Using carbapenems and novel broad-spectrum agents empirically rather than reserving them for confirmed multidrug-resistant infections 1
- Neglecting to address underlying anatomical or functional abnormalities contributing to the UTI 1