What is the recommended antibiotic prophylaxis regimen (dose and duration) for a patient undergoing transrectal ultrasound‑guided prostate biopsy, including alternatives for fluoroquinolone allergy and adjustments for renal impairment?

Antibiotic Prophylaxis for Transrectal Prostate Biopsy

A single dose of oral fluoroquinolone (ciprofloxacin or levofloxacin) given 30-60 minutes before the procedure is the standard prophylaxis for transrectal prostate biopsy, with single-dose regimens proven equally effective as multi-day courses. 1

Standard First-Line Regimen

Single-dose oral fluoroquinolone prophylaxis:

• Levofloxacin 500-750 mg orally given 30-60 minutes before biopsy 2, 3
• Ciprofloxacin 500 mg orally given 30-60 minutes before biopsy 1
• Levofloxacin 750 mg may be superior to ciprofloxacin 500 mg when combined with an aminoglycoside, reducing severe infections from 2.43% to 0.92% (P=0.04) 3

Critical evidence: Multiple RCTs confirm that single-dose or one-day regimens are as effective as three-day regimens for preventing infectious complications after transrectal prostate biopsy. 1 A three-armed RCT of 231 patients demonstrated that a single dose of ciprofloxacin and tinidazole was equally effective as the same combination given twice daily for three days. 1

Duration of Prophylaxis

Prophylaxis should be discontinued within 24 hours after the procedure. 1 Extended antibiotic courses beyond 24 hours do not reduce infection rates and increase the risk of multidrug-resistant organisms. 1

Alternatives for Fluoroquinolone Resistance or Allergy

Given rising fluoroquinolone resistance rates, the 2023 ESCMID guidelines recommend rectal screening to identify fluoroquinolone-resistant Enterobacterales (FQR-E) carriers before transrectal prostate biopsy, with targeted prophylaxis based on culture results. 1

Alternative regimens when fluoroquinolones cannot be used:

Targeted Prophylaxis (Preferred Approach)

• Rectal swab culture performed within 3 weeks before biopsy to guide antibiotic selection 1, 4
• Targeted antibiotics based on susceptibility results 4

Empiric Alternatives

• Fosfomycin trometamol 3g orally before biopsy, then 3g at 24-48 hours post-biopsy 4
• Ceftriaxone 1-2g IV single dose given 30-60 minutes before procedure 4
• Cefixime 400mg orally for 3 days starting 24 hours before biopsy 4
• Gentamicin 5 mg/kg IV single dose given 30-60 minutes before procedure 4
• Amikacin 15 mg/kg IM single dose 4

For patients with documented beta-lactam allergy:

• Gentamicin 1.5 mg/kg IV (maximum 120 mg) as single dose 5
• Fluoroquinolones remain an option if no prior allergy 5

Adjustments for Renal Impairment

Fluoroquinolones:

• Levofloxacin requires dose reduction in renal impairment (CrCl <50 mL/min: reduce to 250-500 mg)
• Ciprofloxacin requires dose reduction in severe renal impairment (CrCl <30 mL/min: reduce to 250-500 mg)

Aminoglycosides:

• Gentamicin and amikacin require dose adjustment and therapeutic monitoring in renal impairment
• Consider alternative agents (ceftriaxone, fosfomycin) in patients with CrCl <30 mL/min to avoid aminoglycoside toxicity

Ceftriaxone:

• No dose adjustment needed for renal impairment (primarily biliary excretion)
• Preferred alternative in patients with significant renal dysfunction 4

High-Risk Patients

For patients at increased risk (diabetes, immunosuppression, large prostate >75cc, severe voiding dysfunction):

• Consider combination prophylaxis with fluoroquinolone plus aminoglycoside 4, 3
• Ampicillin 2g IV plus gentamicin 1.5 mg/kg IV is an alternative high-risk regimen 4
• Augmented prophylaxis with multiple antibiotics may be considered, though this contravenes antibiotic stewardship principles 4

Critical Pitfalls to Avoid

Do not extend prophylaxis beyond 24 hours in an attempt to prevent catheter-associated bacteriuria, as this violates antimicrobial stewardship principles and increases resistance without reducing infection rates. 1, 5

Do not use first-generation cephalosporins (cefazolin) alone for prostate biopsy prophylaxis due to inadequate gram-negative coverage. 4

Ensure proper timing: Administer oral antibiotics 30-60 minutes before the procedure and IV antibiotics 30-60 minutes before to ensure adequate tissue concentrations. 5, 4, 2

Consider local resistance patterns: In areas with high fluoroquinolone resistance (>10-20%), implement rectal swab screening or use alternative empiric regimens. 1, 4

Evidence Quality Note

The recommendation for single-dose prophylaxis is supported by Level Ib evidence from multiple RCTs. 1 The 2023 ESCMID guidelines provide moderate-quality evidence (conditional recommendation) for rectal screening and targeted prophylaxis in the era of increasing fluoroquinolone resistance. 1 Recent research demonstrates that single-dose ertapenem reduced infectious complications from 14.5% to 0.8% compared to 3-day ciprofloxacin (p<0.001), though this is not yet incorporated into major guidelines. 6