What is the optimal management—including antibiotic therapy, metabolic correction, and definitive stone removal—for a patient with a left‑sided staghorn renal calculus, recent fever, urine culture positive for Enterococcus faecium (sensitive), mild renal impairment (creatinine ~65 µmol/L), leukocytosis, and the need for urine alkalinization?

Management of Left-Sided Staghorn Calculus with Complicated UTI

Percutaneous nephrolithotomy (PNL) should be the definitive treatment for this patient after controlling the active infection with appropriate antibiotics, as it offers the highest stone-free rates (superior to SWL monotherapy by more than three times) and is essential to prevent kidney destruction and life-threatening sepsis. 1

Immediate Medical Management (Pre-operative Optimization)

Antibiotic Therapy

• Continue vancomycin 1g IV q12h for Enterococcus faecium coverage, as the organism is sensitive to all tested antibiotics 1
• The current regimen is appropriate given the documented sensitivity pattern
• Complete infection control is mandatory before definitive stone removal to minimize risk of sepsis during surgical manipulation 1
• Duration should continue until clinical signs of infection resolve (fever, leukocytosis) and ideally 48-72 hours of afebrile status before surgery

Critical Pitfall: Alkalinization Strategy

• STOP potassium citrate immediately 2
• Struvite stones form in alkaline urine due to urease-producing bacteria creating ammonia and hydroxide from urea 1, 2
• Alkalinizing the urine with citrate will worsen stone growth by promoting further crystallization of magnesium ammonium phosphate 2
• This is the opposite of uric acid stone management (where alkalinization helps dissolution) 3

Supportive Care

• Continue paracetamol for symptomatic relief
• Continue omeprazole for gastroprotection during antibiotic therapy
• Monitor renal function closely (current creatinine 65 µmol/L is mildly elevated)

Definitive Surgical Management

First-Line Treatment: Percutaneous Nephrolithotomy

PNL monotherapy or PNL-based combination therapy is the standard of care 1, 4

Rationale:

• Stone-free rates with PNL are more than 3 times higher than SWL monotherapy in the only randomized controlled trial 1
• Complete stone removal is the therapeutic goal because bacteria reside within struvite stones (not just on the surface), making partial removal inadequate 1, 2
• Residual fragments will serve as a nidus for recurrent infection and continued stone growth 1
• Untreated staghorn calculi destroy the kidney and cause life-threatening sepsis 1, 2

Combination Therapy Approach:

• If combination therapy is needed, PNL should be the LAST procedure (not first) 1
• SWL may be used for fragments unreachable by flexible nephroscopy, but nephroscopy must follow to assess stone-free status 1
• Nephroscopy is more sensitive than plain radiography for detecting residual fragments 1
• Approaches where SWL was the last step achieved only 23% stone-free rates 1

Alternative Surgical Options (Rarely Indicated)

Open Surgery (Anatrophic Nephrolithotomy):

Consider only if: 1

• Extremely large stones (≥2500 mm²)
• Complex collecting system anatomy with gross dilation
• Extreme morbid obesity precluding fluoroscopic imaging
• Previous failed PNL-based therapy

Do NOT use open surgery as first-line due to higher morbidity, painful flank incisions, 6-week disability, and ~1% mortality risk 1

SWL Monotherapy:

Should NOT be used for most staghorn patients 1

• Produces significantly lower stone-free rates than PNL
• If attempted (against recommendation), requires pre-placement of ureteral stent or nephrostomy tube to prevent obstruction and sepsis 1

Post-Operative Surveillance and Prevention

Immediate Post-Operative Care:

• Confirm stone-free status with non-contrast CT (gold standard) 1
• Continue antibiotics until stone analysis confirms composition
• Monitor for complications: fever, bleeding, urinary leak 5

Long-Term Management:

• Stone analysis is mandatory to guide further therapy 1
• For pure struvite/calcium carbonate apatite stones: 24-hour urine testing is usually NOT necessary (only small percentage have metabolic abnormalities) 1, 6
• For stones with non-struvite components: perform 24-hour urine metabolic evaluation 1, 6
• Prophylactic antibiotics may be needed as patients remain at risk for recurrent UTI even after complete stone removal (22.8% recurrence rate at 40 months) 1

Metabolic Evaluation:

• Despite being infection stones, many staghorn calculi have associated metabolic abnormalities 6
• Metabolic evaluation with directed medical management is recommended for all staghorn stone formers 6
• Address any identified metabolic defects to reduce recurrence risk 1

Summary Algorithm for This Patient:

1. Continue vancomycin until infection controlled (48-72h afebrile, WBC normalizing)
2. STOP potassium citrate (contraindicated in struvite stones)
3. Schedule PNL once infection cleared and patient medically optimized
4. Obtain stone analysis intraoperatively
5. Confirm stone-free status with post-operative CT
6. Consider prophylactic antibiotics long-term to prevent recurrent UTI
7. Metabolic workup if stone contains non-struvite components