Open Access

ARTICLE

Stone culture in patients undergoing percutaneous nephrolithotomy: a practical point of view

Amihay Nevo^1,2, Roy Mano^1,2, Ohad Shoshani^1,2, Gherman Kriderman^1,2, Eran Schreter^1,2, David Lifshitz^1,2

1 Unit of Endourology, Rabin Medical Center, Petah Tikva, Israel
2 Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
Address correspondence to Dr. Amihay Nevo, Unit of Endourology, Rabin Medical Center, Petach Tikva, Israel

Canadian Journal of Urology 2018, 25(2), 9238-9244.

Abstract

Introduction: This study aims to determine the clinical yield of stone culture in patients undergoing percutaneous nephrolithotomy (PCNL) and to identify those who may benefit from this test, particularly in predicting postoperative infections and guiding antimicrobial therapy. Materials and methods: We reviewed our institutional database for all patients who underwent PCNL between 2005 and 2017 and from whom both urine culture (UC) and stone culture (SC) results were available. The primary endpoint was the development of systemic inflammatory response syndrome (SIRS) within 48 hours post-procedure. Risk factors for SIRS and for stone colonization with highly resistant pathogens were evaluated. Based on UC and SC results, we determined the proportion of patients in whom SC would have altered antibiotic management had SIRS occurred, compared to initial empiric treatment. Results: A total of 512 patients were included in the study, with a median age of 53 years; 323 (63%) were male. Positive urine cultures were found in 137 (26.7%) patients, while positive stone cultures were identified in 117 (22.8%). Notably, UC failed to detect the pathogens isolated by SC in 66 (12.8%) patients. Postoperative SIRS occurred in 50 (9.8%) patients. On multivariate analysis, only positive stone culture was significantly associated with the development of SIRS. Resistance rates among SC isolates ranged from 67% for second-generation cephalosporins to 9% for meropenem. Stone culture could have altered antibiotic choice in 73 to 12 patients (14.2% to 2.3% of the entire cohort), respectively, depending on the antibiotic regimen used. Conclusions: Consistent with previous studies, we observed significant discordance between urine and stone culture results, as well as an association between positive stone culture and the development of SIRS. However, the clinical utility of stone culture varies depending on the empiric antibiotic regimen used and is limited when broad-spectrum antibiotics are already administered. These findings suggest that selective use of stone culture may be beneficial in certain high-risk patients undergoing PCNL.

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