For an elderly patient with stage 3 prostate cancer and a pseudomonas infection, who has a surgically inserted suprapubic catheter, should the intravenous (IV) injection of amikacin (15mg/kg) be administered slowly, and is catheter replacement possible?

Amikacin Administration and Suprapubic Catheter Management

Amikacin Infusion Rate

Amikacin 15 mg/kg should be administered as a 30-60 minute intravenous infusion, not as a rapid bolus injection. 1

• The FDA-approved dosing specifies that amikacin should be infused over 30-60 minutes in adults to minimize potential toxicity and optimize pharmacokinetics 1
• For elderly patients specifically, a 30-minute infusion is standard and has been shown to be both practical and safe in multiple clinical trials 2, 3
• Infants and young children require slower administration (1-2 hours), but this does not apply to elderly adults 1
• The once-daily dosing regimen of 15 mg/kg has demonstrated 83.1% primary success rates and 83.9% definitive cure rates in severely infected patients when given as a 30-minute infusion 2

Clinical Rationale: The 30-60 minute infusion time allows for achievement of optimal peak concentrations (approximately 40.9 mg/L with once-daily dosing) while minimizing the risk of concentration-related toxicity 4. Rapid bolus administration is never appropriate for aminoglycosides.

Suprapubic Catheter Replacement

Yes, the surgically-placed suprapubic catheter can and should be replaced, as it is likely the persistent source of your patient's Pseudomonas infection. 5

When to Replace the Catheter

• The catheter should be exchanged or removed once the patient is clinically stable on appropriate antibiotics 5
• The Infectious Diseases Society of America emphasizes that for patients with long-term indwelling catheters and gram-negative bacteremia, serious consideration should be given to catheter removal, especially if bacteremia continues despite appropriate antimicrobial therapy 5
• Even with optimal antibiotics, failure to remove or exchange an infected catheter often results in treatment failure 5

Practical Considerations

• Suprapubic catheters placed surgically can be exchanged using standard catheter exchange techniques—the surgical placement does not preclude replacement 5
• The catheter tract remains patent after surgical placement, allowing for guidewire-assisted or direct catheter exchange by urology 5
• If the catheter cannot be removed entirely, extend antibiotic treatment to 14 days with consideration for combination therapy 5

Treatment Duration Based on Catheter Management

• If catheter is removed: Continue amikacin for 10-14 days total for gram-negative catheter-related bacteremia 5
• If catheter remains in place: Extend treatment to 14 days minimum with consideration for combination therapy 5
• If fever persists beyond 48-72 hours despite optimal amikacin dosing and catheter management, obtain repeat cultures and consider imaging to rule out prostatic abscess or other complications 5

Critical Pitfall to Avoid

The most common error in managing catheter-associated Pseudomonas infections in elderly patients is treating with antibiotics alone without addressing the infected catheter. This approach has a high failure rate regardless of antibiotic choice or duration 5.