What is the recommended approach for treating a urinary tract infection (UTI) in a patient with considerations for age, sex, past medical history, and allergy history?

Management of Urinary Tract Infection

For women with uncomplicated cystitis, treat with first-line agents: fosfomycin trometamol 3g single dose, nitrofurantoin 100mg twice daily for 5 days, or pivmecillinam 400mg three times daily for 3-5 days, reserving trimethoprim-sulfamethoxazole only when local E. coli resistance is <20%. 1

Initial Diagnostic Approach

Women with Typical Lower UTI Symptoms

• Diagnosis can be made clinically without urine culture if patient presents with dysuria, frequency, urgency, suprapubic pain, and no vaginal discharge 2
• Obtain urine culture only if: 1
  • Suspected pyelonephritis (fever >38°C, flank pain, costovertebral angle tenderness)
  • Symptoms persist after treatment or recur within 2-4 weeks
  • Atypical presentation
  • Pregnancy
  • History of resistant organisms
  • Recurrent infections

Men with Lower UTI Symptoms

• Always obtain urine culture before initiating antibiotics 2
• Consider urethritis and prostatitis as alternative diagnoses 2
• Treat for 7 days (not 3-5 days as in women) 1, 2

Antibiotic Selection by Clinical Scenario

Uncomplicated Cystitis in Women

First-Line Options (choose based on availability and patient factors): 1

• Fosfomycin trometamol: 3g single dose
• Nitrofurantoin: 100mg twice daily for 5 days (macrocrystals or monohydrate formulations)
• Pivmecillinam: 400mg three times daily for 3-5 days

Alternative Agents (use only when first-line unavailable or contraindicated): 1

• Trimethoprim-sulfamethoxazole: 160/800mg twice daily for 3 days (only if local E. coli resistance <20%)
• Trimethoprim alone: 200mg twice daily for 5 days (avoid first trimester pregnancy)
• Cephalosporins (e.g., cefadroxil): 500mg twice daily for 3 days (only if local E. coli resistance <20%)

Important caveat: Fluoroquinolones and β-lactams should not be used as first-line empiric therapy for uncomplicated cystitis due to collateral damage (ecological adverse effects) and inferior efficacy respectively 1, 3

Uncomplicated Cystitis in Men

Treat for 7 days with: 1, 2

• Trimethoprim-sulfamethoxazole: 160/800mg twice daily for 7 days
• Trimethoprim: 200mg twice daily for 7 days
• Nitrofurantoin: 100mg twice daily for 7 days
• Fluoroquinolones may be used according to local susceptibility patterns 1

Uncomplicated Pyelonephritis

Obtain urine culture in all cases 1

Oral empiric therapy (for outpatient management): 1

• Fluoroquinolones (ciprofloxacin or levofloxacin) are first-line oral agents
• Oral cephalosporins achieve lower blood levels than fluoroquinolones but may be used 1

Imaging considerations: 1

• Perform renal ultrasound if: history of urolithiasis, renal dysfunction, high urine pH, or no improvement after 72 hours
• Consider CT scan immediately if clinical deterioration occurs 1

Complicated UTI (with structural/functional abnormalities, immunosuppression, or healthcare-associated)

Always obtain urine culture before treatment 1

Empiric IV therapy for systemic symptoms: 1

• Amoxicillin plus aminoglycoside, OR
• Second-generation cephalosporin plus aminoglycoside, OR
• Third-generation cephalosporin IV

Oral therapy considerations: 1

• Use ciprofloxacin only if local resistance <10% AND patient has β-lactam anaphylaxis OR doesn't require hospitalization
• Avoid fluoroquinolones if patient used them in last 6 months or is from urology department 1

Treatment duration: 7-14 days (14 days for men when prostatitis cannot be excluded) 1

Treatment Failure Management

If symptoms persist at end of treatment or recur within 2 weeks: 1

• Obtain urine culture with susceptibility testing
• Assume organism is resistant to initially used agent
• Retreat with different antibiotic for 7 days 1
• Consider nitrofurantoin for retreatment as resistance decays quickly 1

Recurrent UTI Prevention (≥3 UTIs/year or ≥2 in 6 months)

Stepwise approach - attempt interventions in this order: 1

Step 1: Non-antimicrobial Measures

Postmenopausal women: 1

• Vaginal estrogen replacement (strong recommendation)
• Consider adding lactobacillus-containing probiotics 1

Premenopausal women: 1

• Increase fluid intake
• For post-coital infections: low-dose antibiotic within 2 hours of intercourse for 6-12 months 1

All patients: 1

• Immunoactive prophylaxis (strong recommendation)
• Methenamine hippurate for women without urinary tract abnormalities (strong recommendation)
• Cranberry products (weak evidence, contradictory findings)
• D-mannose (weak evidence, contradictory findings)

Step 2: Antimicrobial Prophylaxis (when non-antimicrobial measures fail)

Continuous daily prophylaxis: 1

• Nitrofurantoin 50mg daily
• Trimethoprim-sulfamethoxazole 40/200mg daily
• Trimethoprim 100mg daily
• Avoid fluoroquinolones and cephalosporins for prophylaxis 1
• Consider rotating antibiotics every 3 months to prevent resistance 1

Alternative: Self-administered short-term therapy at symptom onset for compliant patients 1

Step 3: Invasive Options (when less invasive approaches fail)

• Endovesical instillations of hyaluronic acid or hyaluronic acid/chondroitin sulfate combination 1

Special Populations

Asymptomatic Bacteriuria

Do NOT screen or treat in: 1

• Non-pregnant women without risk factors
• Patients with well-controlled diabetes
• Postmenopausal women
• Elderly institutionalized patients
• Patients with neurogenic bladder or reconstructed urinary tract
• Renal transplant recipients
• Patients before arthroplasty

DO screen and treat: 1

• Pregnant women (use standard short-course or single-dose fosfomycin)
• Before urological procedures breaching mucosa

Catheter-Associated UTI

• Mortality rate approximately 10% when bacteremia develops 1
• Catheter duration is most important risk factor 1
• Treat only symptomatic infections (fever, rigors, altered mental status, flank pain, or dysuria after catheter removal) 1

Women with Diabetes

• Treat acute cystitis same as women without diabetes if no voiding abnormalities present 3

Elderly Patients (≥65 years)

• Obtain urine culture with susceptibility testing 2
• Use same first-line antibiotics and durations as younger adults 2
• Note that genitourinary symptoms may not correlate with cystitis in elderly women 1

Critical Pitfalls to Avoid

• Never use fluoroquinolones as first-line for uncomplicated cystitis - reserve for pyelonephritis and complicated infections 1, 3
• Do not treat asymptomatic bacteriuria except in pregnancy or before mucosal-breaching procedures - this increases resistance and recurrence 1
• Avoid extensive workup (cystoscopy, full abdominal ultrasound) in women <40 years with recurrent UTI and no risk factors 1
• Do not use single-dose antibiotics - associated with higher bacteriological persistence 1
• Avoid classifying patients with recurrent UTI as "complicated" unless true structural/functional abnormalities exist - this leads to unnecessary broad-spectrum antibiotic use 1