The Modern Era Struvite Stone: Pa erns of InfecPon and ColonizaPon
The Modern Era Struvite Stone: Pa3erns of Infec8on and Coloniza8on Dr Haresh G Thummar,Adam De Fazio1, Piruz M,1, Usama K,, Mantu Gupta2 2 Department of Urology, Mount Sinai St. Luke’s Roosevelt, New York, NY
1 Department of Urology, Columbia University College of Physicians and Surgeons, New York, NY
INTRODUCTION AND OBJECTIVES Consistent with the prevailing model of struvite stone forma5on, observa5onal studies from the 1970s and 1980s demonstrated a strong associa5on between magnesium ammonium phosphate (MAP) containing stones and urea-‐spliDng organisms on stone culture.1-‐4 Subsequent studies from the 1990s reported a notable decrease in the percentage of struvite stones associated with urea-‐spliDng organisms (see fig. 1).5-‐6 The apparent weakening of the associa5on between MAP containing stones and urea-‐spliDng organisms prompted considera5on of (1) stone steriliza5on in the seDng of increased fluoroquinolone use and (2) the possibility of struvite forma5on in the absence of urea-‐ spliDng organisms. Nearly 20 years have passed since the publica5on of the last major observa5onal study on struvite stone forma5on. We sought to offer a modern assessment of struvite stone forma5on by revisi5ng the associa5on between MAP and urea spliDng organisms. We also aimed to expand on prior studies by analyzing demographic characteris5cs, clinical history and pre-‐opera5ve an5bio5c use by struvite formers.
METHODS
Struvite Non-‐ P-‐value Struvite
We retrospec5vely iden5fied pa5ents with renal calculi who underwent percutaneous nephrolithotomy (PCNL) performed by a single urologist between February 2009 and August 2013. Renal transplant recipients and pa5ents who underwent PCNL for ureteral stones or Indiana pouch stones were excluded from the study. A\er exclusion, 474 total pa5ents were assessed. Basic demographic data was collected. Past medical history was reviewed for recurrent UTI and the presence of host-‐dependent UTI risk factors. UTI risk factors were categorized as obstruc5ve, neurogenic, foreign body, impaired host defense and other. The use of an5bio5cs at any point between diagnosis of the treated renal calculus and PCNL was recorded. The results of stone cultures were reviewed. Data was collected on urine cultures obtained Intraopera5vely, pre-‐opera5vely and during the 12 months prior to PCNL.
RESULTS
Of the 474 pa5ents in this series, only 8% were struvite formers. While there was no difference in mean age between struvite and non-‐struvite formers, there was a sta5s5cally significant difference in gender distribu5on with a predominance of females in the struvite group (see table 1). 60% (23/35) of struvite formers exhibited at least one UTI risk factor (see table 2) and 89% (31/35) reported a history of recurrent UTI. An5bio5cs were given to 86% (30/35) of struvite formers prior to PCNL. 69% of struvite stones were associated with a posi5ve stone culture compared to 23% of non-‐ struvite stones (P
1 Department of Urology, Columbia University College of Physicians and Surgeons, New York, NY
INTRODUCTION AND OBJECTIVES Consistent with the prevailing model of struvite stone forma5on, observa5onal studies from the 1970s and 1980s demonstrated a strong associa5on between magnesium ammonium phosphate (MAP) containing stones and urea-‐spliDng organisms on stone culture.1-‐4 Subsequent studies from the 1990s reported a notable decrease in the percentage of struvite stones associated with urea-‐spliDng organisms (see fig. 1).5-‐6 The apparent weakening of the associa5on between MAP containing stones and urea-‐spliDng organisms prompted considera5on of (1) stone steriliza5on in the seDng of increased fluoroquinolone use and (2) the possibility of struvite forma5on in the absence of urea-‐ spliDng organisms. Nearly 20 years have passed since the publica5on of the last major observa5onal study on struvite stone forma5on. We sought to offer a modern assessment of struvite stone forma5on by revisi5ng the associa5on between MAP and urea spliDng organisms. We also aimed to expand on prior studies by analyzing demographic characteris5cs, clinical history and pre-‐opera5ve an5bio5c use by struvite formers.
METHODS
Struvite Non-‐ P-‐value Struvite
We retrospec5vely iden5fied pa5ents with renal calculi who underwent percutaneous nephrolithotomy (PCNL) performed by a single urologist between February 2009 and August 2013. Renal transplant recipients and pa5ents who underwent PCNL for ureteral stones or Indiana pouch stones were excluded from the study. A\er exclusion, 474 total pa5ents were assessed. Basic demographic data was collected. Past medical history was reviewed for recurrent UTI and the presence of host-‐dependent UTI risk factors. UTI risk factors were categorized as obstruc5ve, neurogenic, foreign body, impaired host defense and other. The use of an5bio5cs at any point between diagnosis of the treated renal calculus and PCNL was recorded. The results of stone cultures were reviewed. Data was collected on urine cultures obtained Intraopera5vely, pre-‐opera5vely and during the 12 months prior to PCNL.
RESULTS
Of the 474 pa5ents in this series, only 8% were struvite formers. While there was no difference in mean age between struvite and non-‐struvite formers, there was a sta5s5cally significant difference in gender distribu5on with a predominance of females in the struvite group (see table 1). 60% (23/35) of struvite formers exhibited at least one UTI risk factor (see table 2) and 89% (31/35) reported a history of recurrent UTI. An5bio5cs were given to 86% (30/35) of struvite formers prior to PCNL. 69% of struvite stones were associated with a posi5ve stone culture compared to 23% of non-‐ struvite stones (P
