<prompt> Commonest stone in case of UTI -PhosphateUrateCysteineCalcium oxalate  <response>: Ans is a ie Phosphate Phosphate or struvite stones are infection stones associated with urea splitting organisms i.e. Proteus, Pseudomonas, Providincia, Klebsiella, Staphylococci and Mycoplasma. The high ammonium concentration desired from urea-splitting organisms results in an alkaline urinary pH, reauired for the precipitation of phosphate crystals. 