A 77-year-old female presented with bilateral staghorn calculi. She underwent an uneventful left percutaneous nephrolithotomy (PCNL); the stone analysis revealed a 90% struvite and 10% calcium phosphate stone. Treatment of the right stone was postponed by the patient. During the next 9 months, her family physician gave her multiple courses of culture-directed antibiotics due to breakthrough urinary-tract infections, despite her also being on a prophylactic antibiotic. After 9 months, she agreed to undergo her right PCNL. Preoperatively, a non-contrast CT scan was obtained; it revealed complete resolution of the right staghorn calculi.