What is the best antibiotic regimen for treating urinary tract infections (UTIs) in a hospital ward setting?

Best Antibiotic for UTI in Ward Setting

For hospitalized patients with complicated UTIs, initiate empiric parenteral therapy with either a carbapenem (meropenem 1g IV q8h or imipenem/cilastatin 0.5g IV q8h), a newer β-lactam/β-lactamase inhibitor combination (ceftazidime/avibactam 2.5g IV q8h or ceftolozane/tazobactam 1.5g IV q8h), or an aminoglycoside (gentamicin 5 mg/kg IV once daily), with the specific choice guided by local resistance patterns and patient risk factors for multidrug-resistant organisms. 1

Initial Empiric Parenteral Therapy

First-Line Options Based on Resistance Risk

For patients WITHOUT known multidrug-resistant organism risk:

• Ceftriaxone 2g IV once daily is an excellent initial choice for complicated UTIs, providing broad-spectrum coverage against common uropathogens including E. coli, Proteus, and Klebsiella with excellent urinary concentrations 1
• Aminoglycosides (gentamicin 5 mg/kg IV once daily or amikacin 15 mg/kg IV once daily) are recommended first-line therapy, particularly if prior fluoroquinolone resistance is suspected 1

For patients WITH multidrug-resistant organism risk (prior MDR isolation, recent healthcare exposure, or early culture results showing resistance):

• Carbapenems: meropenem 1g IV q8h, imipenem/cilastatin 0.5g IV q8h, or meropenem-vaborbactam 2g IV q8h 1, 2
• Novel β-lactam/β-lactamase inhibitor combinations: ceftazidime/avibactam 2.5g IV q8h, ceftolozane/tazobactam 1.5g IV q8h, or cefiderocol 2g IV q8h 1, 2

For carbapenem-resistant Enterobacteriaceae (CRE):

• Meropenem-vaborbactam 2g IV q8h showed superiority over best available therapy in the TANGO-II trial 2
• Plazomicin 15 mg/kg IV q12h specifically for CRE-associated UTIs, with the CARE trial demonstrating fewer deaths (24% vs 50%) and lower acute kidney injury (16.7% vs 50%) compared to colistin-based regimens 1, 2
• Ceftazidime-avibactam 2.5g IV q8h is highly effective for KPC-producing organisms 2

Oral Step-Down Therapy

Transition to oral therapy when the patient is clinically improved, hemodynamically stable, and afebrile for at least 48 hours: 1

Preferred Oral Options (Based on Susceptibility)

• Fluoroquinolones (ONLY if local resistance <10% and organism is susceptible): ciprofloxacin 500-750 mg PO twice daily for 7 days or levofloxacin 750 mg PO once daily for 5 days 1, 3
• Trimethoprim-sulfamethoxazole 160/800 mg (1 DS tablet) PO twice daily for 10-14 days 1, 4
• Oral cephalosporins: cefpodoxime 200 mg PO twice daily for 10 days, ceftibuten 400 mg PO once daily for 10 days, or cefuroxime 500 mg PO twice daily for 10-14 days 1
• Amoxicillin-clavulanate 875/125 mg PO twice daily can be used for susceptible organisms 5, 6

Treatment Duration

• Standard duration: 7-14 days total (parenteral plus oral) 1
• 7 days is appropriate for patients with prompt resolution of symptoms who are hemodynamically stable and afebrile for ≥48 hours 1
• 14 days is recommended for:
  • Male patients (all male UTIs are considered complicated and may involve prostate) 1, 7
  • Patients with delayed clinical response 1
  • When prostatitis cannot be excluded 1

Critical Management Principles

Always obtain urine culture BEFORE initiating antibiotics to guide targeted therapy, as complicated UTIs have a broader microbial spectrum including E. coli, Proteus spp., Klebsiella spp., Pseudomonas spp., Serratia spp., and Enterococcus spp. 1, 2

Adjust therapy based on culture results and susceptibility patterns within 48-72 hours of obtaining results 1, 2

Address underlying urological abnormalities (obstruction, foreign bodies, incomplete voiding) as antimicrobial therapy alone is insufficient without source control 1, 2

Replace indwelling catheters that have been in place ≥2 weeks at treatment onset to hasten symptom resolution and reduce recurrence risk 1

Reassess patients at 72 hours if there is no clinical improvement with defervescence, as extended treatment and urologic evaluation may be needed 1

Common Pitfalls to Avoid

• Do NOT use fluoroquinolones empirically if local resistance exceeds 10% or if the patient received fluoroquinolones in the last 6 months 1, 2
• Avoid carbapenems as first-line empiric therapy unless early culture results indicate multidrug-resistant organisms, to preserve their effectiveness 2
• Do NOT rely on oral agents alone for severe complicated UTIs with multidrug resistance—parenteral therapy is essential initially 2
• Do NOT use moxifloxacin for UTI treatment due to uncertainty regarding effective urinary concentrations 1
• Do NOT treat asymptomatic bacteriuria in catheterized patients, as this leads to inappropriate antimicrobial use and resistance 1
• Failing to replace long-term catheters at treatment initiation can reduce treatment efficacy 1

Special Populations

Male patients: All UTIs in males are considered complicated and require 7-14 days of treatment (14 days when prostatitis cannot be excluded) 1, 7

Patients with ESBL-producing organisms: Oral options include nitrofurantoin, fosfomycin, pivmecillinam, amoxicillin-clavulanate (for E. coli only); parenteral options include carbapenems, piperacillin-tazobactam (for E. coli only), ceftazidime-avibactam, and aminoglycosides 6

Multidrug-resistant Pseudomonas: Treatment options include ceftolozane-tazobactam, ceftazidime-avibactam, cefiderocol, imipenem-cilastatin/relebactam, and aminoglycosides 6