A 45-year-old woman with recurrent urinary tract infection has a complete staghor ncalculus filling the right renal pelvis and calyces. Which organism is classically associated with this type of stone, and what is the definitive treatment?
- A Escherichia coli, extracorporeal shock wave lithotripsy alone
- B Pseudomonas aeruginosa, open nephrolithotomy
- C Proteus species, percutaneous nephrolithotomy ✓
- D Klebsiella pneumoniae, ureteroscopy with laser lithotripsy
Correct answer: C. Proteus species, percutaneous nephrolithotomy
Explanation
Staghorn calculi are struvite stones, magnesium ammonium phosphate, formed when urease producing organisms such as Proteus split urea, alkalinising the urine and precipitating triple phosphate. Complete staghorn stones require percutaneous nephrolithotomy for clearance because shock wave lithotripsy alone leaves fragments that act as a nidus for recurrence and ongoing infection.
Reference: Smith's General Urology, 18th ed.
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