Haresh Thummar, Adam De Fazio, Michael Rothberg, Piruz Motamedinia, Gina Badalato and Mantu Gupta
Posters-Accepted Abstracts: Med Surg Urol
Introduction & Objectives: We sought to offer a modern assessment of struvite stone formation by examining both the characteristics of struvite formers and the nature of associated infectious organisms. Methods: We retrospectively identified patients who underwent PCNL between February 2009 and August 2013. Predisposing characteristics and clinical history of UTI were assessed. Urine cultures (pre-operative clean catch and intra-operative renal pelvis) and stone cultures were reviewed for infection. Results: Struvite formers represented 38 (8%) of 474 patients identified. 82% of struvite formers were female (vs. 47% in nonstruvite formers, P<) while 94% reported recurrent/recent UTI and 60% exhibited a UTI risk factor. A greater percentage of struvite formers demonstrated growth on pre-operative urine (46% vs. 22%, P<), intra-operative urine (10% vs. 7%, P<) and stone culture (69% vs. 23%, P<) when compared to non-struvite formers. Similar differences were found when considering only urea-splitting organisms pre-operatively (31% vs. 10%, P<), intra-operatively (3% vs. 2%, P<) and within retrieved stones (29% vs. 10%, P<). 31% of struvite stones were sterile and 49% grew non-urea splitting organisms including E. coli and Enterococcus spp. Conclusions: Urea-splitting organisms could not be identified in association with all struvite formers in this series. The presence of sterile stones prompts consideration of antibiotic mediated sterilization and lends support to pre-operative antibiotic use. The presence of traditionally non-urea-splitting organisms encourages re-evaluation of their urea-splitting potential and reveals the importance of expanded antibiotic coverage for both Enterococcus spp and E. coli in managing suspected struvite stones.
