What is the best antibiotic (abx) for this patient based on the urine culture and sensitivity (C & S) results?

Best Antibiotic Selection for E. coli UTI with Fluoroquinolone Resistance

For this E. coli urinary tract infection with documented fluoroquinolone resistance, nitrofurantoin is the optimal first-line oral antibiotic choice, given its excellent susceptibility profile (≤32 S), proven efficacy, and minimal resistance patterns. 1

Primary Recommendation: Nitrofurantoin

Nitrofurantoin should be prescribed at 100 mg twice daily for 5-7 days. 1 This organism shows full susceptibility (MIC ≤32, S), making nitrofurantoin an ideal choice. 2, 3

• Nitrofurantoin maintains 95-96% susceptibility rates against E. coli despite decades of use, with only 2.3% resistance rates in community settings. 3
• The 2024 European Association of Urology guidelines explicitly recommend nitrofurantoin as first-line therapy for uncomplicated cystitis. 1
• Clinical cure rates of 92.3% at 12-16 days post-treatment have been demonstrated. 4

Alternative Oral Options (In Order of Preference)

Second Choice: Cephalosporins

Cefazolin (≤2 S) or ceftriaxone (≤1 S) are excellent alternatives if nitrofurantoin cannot be used. 1

• For oral therapy, cefpodoxime 200 mg twice daily for 10 days or ceftibuten 400 mg daily for 10 days are appropriate. 1
• First-generation cephalosporins like cefadroxil 500 mg twice daily for 3 days can be used if local E. coli resistance is <20%. 1

Third Choice: Ampicillin-Based Agents

Ampicillin/sulbactam (≤8/4 S) or ampicillin (≤8 S) are viable options. 1

• Oral amoxicillin-clavulanate 875 mg twice daily can be prescribed. 1
• These beta-lactam combinations overcome common E. coli resistance mechanisms. 1

Agents to AVOID

Do NOT use ciprofloxacin (>2 R) or levofloxacin (>4 R) - the culture shows documented resistance. 1

Do NOT use trimethoprim/sulfamethoxazole (>2/38 R) - the organism is resistant. 1

• The 2024 EAU guidelines explicitly state fluoroquinolones should not be used for empirical treatment when patients have used them in the last 6 months or when resistance is documented. 1

Parenteral Options (If Oral Therapy Fails or Severe Infection)

If the patient requires IV therapy due to systemic symptoms or treatment failure, use ceftriaxone 1-2 grams daily. 1

• Gentamicin 5 mg/kg daily or tobramycin (both ≤2 S) are alternative aminoglycoside options. 1
• Piperacillin/tazobactam (≤8 S) at 3.375 grams every 6 hours is another parenteral choice. 1
• Ertapenem (≤0.5 S) or meropenem/vaborbactam (≤2 S) should be reserved for complicated infections or multidrug-resistant organisms. 1

Critical Clinical Considerations

Determine if this is uncomplicated cystitis versus pyelonephritis or complicated UTI, as this fundamentally changes management. 1

• For uncomplicated cystitis in women: 5-7 days of nitrofurantoin is sufficient. 1
• For pyelonephritis: avoid nitrofurantoin (inadequate tissue penetration) and use ceftriaxone or parenteral therapy for 7-14 days. 1
• For complicated UTI (males, obstruction, instrumentation, immunosuppression): 7-14 days of therapy is required. 1

Assess for complicating factors that would classify this as a complicated UTI: 1

• Male patient
• Urinary obstruction or foreign body (catheter)
• Recent instrumentation
• Diabetes mellitus or immunosuppression
• Healthcare-associated infection

Nitrofurantoin has important contraindications: 2, 5, 6

• Avoid if CrCl <30 mL/min (efficacy significantly reduced). 5
• Use with caution if CrCl 30-60 mL/min, though recent data suggests acceptable efficacy in this range. 5
• Contraindicated in last trimester of pregnancy. 1
• Not appropriate for pyelonephritis due to inadequate tissue concentrations. 1

Duration of Therapy

For uncomplicated cystitis: 5-7 days of nitrofurantoin. 1

For complicated UTI or male patients: 7-14 days (14 days if prostatitis cannot be excluded). 1

For pyelonephritis: 7-14 days of appropriate therapy (not nitrofurantoin). 1