What is the optimal antibiotic choice and dosing regimen for treating a Serratia marcescens infection in a patient with end‑stage renal disease (chronic kidney disease stage 5, estimated glomerular filtration rate <15 mL/min/1.73 m²) on intermittent hemodialysis?

Antibiotic Selection and Dosing for Serratia marcescens in CKD Stage 5

For Serratia marcescens infection in a patient with CKD stage 5 on hemodialysis, initiate piperacillin-tazobactam 2.25 g IV every 8 hours (or 3.375 g IV every 8 hours for severe infections), with dosing after dialysis on dialysis days, as this agent has demonstrated superior clinical efficacy in this population and requires no dose adjustment beyond standard hemodialysis timing considerations.

Primary Antibiotic Choice

Piperacillin-tazobactam is the preferred empiric and definitive agent for Serratia marcescens in end-stage renal disease. 1 This recommendation is based on a case report demonstrating successful treatment of relapsing Serratia peritonitis in a dialysis patient where ceftazidime failed despite in vitro sensitivity, but piperacillin-tazobactam monotherapy achieved clinical cure. 1

Alternative Agents Based on Susceptibility

• Ceftazidime can be used if susceptibility is confirmed, but clinical failures have been documented even with in vitro sensitivity in dialysis patients 1
• Fluoroquinolones (ciprofloxacin, levofloxacin) are effective against Serratia and commonly used 2, 3
• Aminoglycosides (gentamicin) have activity but require careful monitoring in residual renal function 2, 3
• Carbapenems should be reserved for resistant strains given their broad spectrum 2

Dosing Regimens for CKD Stage 5 on Hemodialysis

Piperacillin-Tazobactam

• Standard dosing: 2.25 g IV every 8 hours 4
• Severe infections: 3.375 g IV every 8 hours 4
• Timing: Administer after hemodialysis on dialysis days 4
• No additional supplementation needed between dialysis sessions 4

Ciprofloxacin (if susceptible)

• Dosing: 500 mg loading dose, then 250 mg every 24 hours for creatinine clearance <10 mL/min 4
• Oral bioavailability makes this convenient for outpatient therapy 4

Levofloxacin (if susceptible)

• Dosing: 500 mg loading dose, then 250 mg every 48 hours for creatinine clearance <50 mL/min 4
• Alternative: 750 mg loading dose with adjusted maintenance 4

Ceftazidime (if susceptible, though less preferred)

• Dosing: 1 g IV every 24-48 hours for creatinine clearance <10 mL/min 4
• Supplemental dose: Give after hemodialysis 4

Gentamicin (if susceptible, use with caution)

• Dosing: 3.0-5.0 mg/kg IV every 24 hours even in hemodialysis 4
• Monitoring: Requires therapeutic drug monitoring due to narrow therapeutic window 4
• Risk: Can eliminate residual renal function 4

Critical Clinical Considerations

High-Risk Features in Dialysis Patients

Serratia marcescens causes severe infections in end-stage renal disease patients with high rates of catheter loss and mortality. 1, 5, 6 Risk factors include:

• Peritoneal dialysis catheters - high risk for relapsing peritonitis requiring catheter removal 1, 3
• Hemodialysis access sites - can progress to necrotizing fasciitis 5, 6
• Open wounds or calciphylaxis - associated with life-threatening soft tissue infections 5
• Immunocompromised state inherent to uremia 6

Treatment Failure Recognition

Rapid escalation is essential if clinical deterioration occurs despite appropriate antibiotics. 1 Warning signs include:

• Persistent cloudy dialysate after 48-72 hours of antibiotics in peritoneal dialysis 1, 3
• Worsening abdominal pain despite therapy 3
• Progression to septic shock 6
• Failure of WBC count to decline in peritoneal fluid 3

When to Remove Catheters

Peritoneal dialysis catheter removal should occur promptly if: 1, 3

• No clinical improvement after 5 days of appropriate antibiotics 1
• Relapsing infection (second episode within 4 weeks) 1
• Rapid clinical deterioration or septic shock 1, 6
• Persistent peritonitis despite sensitivity-guided therapy 3

Antibiotic Resistance Patterns

Serratia marcescens demonstrates multiple resistance mechanisms including beta-lactamases, and susceptibility testing is mandatory. 2 Common resistance includes:

• Intrinsic resistance to ampicillin and first-generation cephalosporins 2
• Variable susceptibility to third-generation cephalosporins 2
• Generally susceptible to fluoroquinolones, aminoglycosides, and piperacillin-tazobactam 2

Monitoring Parameters

For patients with eGFR <15 mL/min/1.73 m² on dialysis: 4

• Baseline: Obtain cultures before antibiotics, check electrolytes and residual renal function 4
• During therapy: Monitor clinical response daily, repeat cultures if no improvement by 48-72 hours 1, 3
• Drug levels: Obtain aminoglycoside levels if used (peak and trough) 4
• Dialysis timing: Coordinate antibiotic administration with dialysis schedule 4

Source Control

Surgical debridement is mandatory for necrotizing soft tissue infections, which can occur with Serratia in dialysis patients. 5, 6 Early surgical consultation should occur if:

• Cellulitis progresses despite antibiotics 6
• Signs of necrotizing fasciitis develop (crepitus, rapid spread, systemic toxicity) 5
• Abscess formation at access sites 6