How to manage a urinary tract infection (UTI)?

Management of Urinary Tract Infection (UTI)

Initiate empiric antibiotic therapy immediately based on local resistance patterns, obtain urine culture before starting treatment, and adjust therapy according to susceptibility results—treating for 7-14 days depending on infection severity and patient factors. 1

Initial Assessment and Diagnosis

Before initiating treatment, proper diagnosis is critical:

• Obtain urine culture via catheterization or suprapubic aspiration in febrile infants 2-24 months to document true UTI and guide antimicrobial management 1
• Significant bacteriuria is defined as ≥50,000 CFUs/mL of a single uropathogen with urinalysis demonstrating bacteriuria or pyuria in children 1
• Urine culture and susceptibility testing should be performed in all complicated UTIs before initiating empiric therapy 1
• Avoid treating asymptomatic bacteriuria as this fosters antimicrobial resistance and increases recurrent UTI episodes 1

Empiric Antibiotic Selection

For Uncomplicated Cystitis (Adults)

First-line oral agents (choose based on local resistance patterns):

• Nitrofurantoin (preferred when resistance is low, as resistance decays quickly) 1, 2
• Fosfomycin 2
• Pivmecillinam 2
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 14 days only if local resistance is <10-20% 1, 3, 4

Avoid trimethoprim-sulfamethoxazole if local resistance exceeds 10-20%, as resistance now approaches 18-22% in many U.S. regions and is associated with poorer clinical outcomes 4

For Uncomplicated Pyelonephritis (Adults)

Oral therapy options:

• Ciprofloxacin 500-750 mg twice daily for 7 days (if fluoroquinolone resistance <10%) 1
• Levofloxacin 750 mg daily for 5 days 1
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 14 days 1
• Cefpodoxime 200 mg twice daily for 10 days (administer initial IV dose of ceftriaxone first) 1

Parenteral therapy options (for toxic-appearing or unable to tolerate oral):

• Ceftriaxone 1-2 g daily 1
• Ciprofloxacin 400 mg twice daily 1
• Levofloxacin 750 mg daily 1
• Piperacillin/tazobactam 2.5-4.5 g three times daily 1

For Febrile Infants/Children (2-24 months)

Parenteral options (for toxic appearance or unable to retain oral intake):

• Ceftriaxone 75 mg/kg every 24 hours 1
• Cefotaxime 150 mg/kg/day divided every 6-8 hours 1
• Gentamicin 7.5 mg/kg/day divided every 8 hours 1

Oral options (equally efficacious to parenteral in non-toxic children):

• Amoxicillin-clavulanate 20-40 mg/kg/day in 3 doses 1
• Cefixime 8 mg/kg/day in 1 dose 1
• Cefpodoxime 10 mg/kg/day in 2 doses 1
• Trimethoprim-sulfamethoxazole 6-12 mg/kg trimethoprim component per day in 2 doses 1

Critical caveat: Avoid nitrofurantoin in febrile infants as it does not achieve therapeutic bloodstream concentrations needed to treat pyelonephritis or urosepsis 1

Treatment Duration

• Uncomplicated cystitis: 3-7 days depending on antibiotic chosen 5, 2
• Uncomplicated pyelonephritis: 5-14 days depending on agent (fluoroquinolones 5-7 days, others 10-14 days) 1
• Febrile UTI in children: 7-14 days total (courses <7 days are inferior) 1
• Complicated UTI: 7-14 days (14 days for men when prostatitis cannot be excluded) 1
• Shorter duration (7 days) acceptable when patient is hemodynamically stable and afebrile for ≥48 hours 1

Complicated UTI Considerations

Factors defining complicated UTI include: 1

• Urinary tract obstruction at any site
• Foreign body or catheter
• Male sex
• Pregnancy
• Diabetes mellitus
• Immunosuppression
• Recent instrumentation
• Multidrug-resistant organisms

Management principles:

• Address underlying urological abnormality—this is mandatory 1
• Broader microbial spectrum expected: E. coli, Proteus, Klebsiella, Pseudomonas, Serratia, Enterococcus 1
• Higher antimicrobial resistance likely 1
• Reserve carbapenems and novel broad-spectrum agents only for early culture results indicating multidrug-resistant organisms 1

Symptomatic Relief

• Phenazopyridine for symptomatic relief of pain, burning, urgency, and frequency 6
• Do not use phenazopyridine for >2 days as there is no evidence that combined administration with antibiotics provides greater benefit after 2 days 6
• Consider ibuprofen for pain relief while awaiting diagnostic measures, as risk of uncomplicated UTI progressing to pyelonephritis is low (1-2%) 2

Follow-Up and Monitoring

• Adjust antimicrobial therapy according to culture sensitivities 1
• Follow-up in 1-2 days to ensure risk factors have not emerged that would increase UTI risk 1
• If symptoms persist despite treatment, repeat urine culture to assess for ongoing bacteriuria before prescribing additional antibiotics 1
• Switch from parenteral to oral therapy when clinical improvement occurs (generally 24-48 hours) and patient can retain oral fluids 1

Imaging in Pediatric Patients

• Obtain renal and bladder ultrasonography (RBUS) in febrile infants with UTI to detect anatomic abnormalities 1
• Timing: Ideally within 48 hours for early detection and treatment to reduce risk of renal scarring 1
• Consider voiding cystourethrography (VCUG) after second UTI or if RBUS indicates need, to evaluate for grade IV-V vesicoureteral reflux 1

Common Pitfalls to Avoid

• Do not use single effective agents as "combination therapy" for initial uncomplicated UTI episodes 3
• Do not delay definitive diagnosis when using symptomatic relief agents like phenazopyridine 6
• Do not classify recurrent UTI patients as "complicated" unless they have structural/functional abnormalities or immunosuppression, as this leads to unnecessary broad-spectrum antibiotic use 1
• Do not use fluoroquinolones empirically if local resistance exceeds 10% 1