Patrick A Cockerill1, Marcelino E Rivera1, Amy E Krambeck2. 1. Department of Urology, Mayo Clinic, Rochester, MN. 2. Department of Urology, Mayo Clinic, Rochester, MN. Electronic address: Krambeck.Amy@mayo.edu.
Abstract
OBJECTIVE: To define the sensitivity and specificity of stone gram stain for infected urolithiasis treated with percutaneous nephrolithotomy (PCNL). METHODS: PCNL procedures performed at our institution were analyzed between January 2009 and May 2013. Stone fragments were sent in a sterile fashion for aerobic and fungal cultures. A gram stain and fungal smear were performed on the stones and reported within 24 hours of collection. RESULTS: A total of 228 patients underwent 248 PCNLs. Of the 248 stones, 81 (33%) had a positive stone culture. Stone gram stain was positive in 31 cases and negative in 50. There were 167 negative stone cultures, and in these cases, gram stain was positive in 5 and negative in 162. The calculated sensitivity and specificity of stone gram stain were 38% and 97%. The positive and negative predictive values were 86% and 76%, respectively. In the subset of 16 patients with positive stone fungal cultures, fungal smear was performed in 12 and was positive in 4, giving fungal smear a sensitivity of 33%. CONCLUSION: The results of this study suggest that stone gram stain cannot be relied on to detect a positive stone culture and may fail to detect up to 62% of infected stones. However, when positive, gram stain accurately predicts a positive stone culture in 86% of cases.
OBJECTIVE: To define the sensitivity and specificity of stone gram stain for infected urolithiasis treated with percutaneous nephrolithotomy (PCNL). METHODS: PCNL procedures performed at our institution were analyzed between January 2009 and May 2013. Stone fragments were sent in a sterile fashion for aerobic and fungal cultures. A gram stain and fungal smear were performed on the stones and reported within 24 hours of collection. RESULTS: A total of 228 patients underwent 248 PCNLs. Of the 248 stones, 81 (33%) had a positive stone culture. Stone gram stain was positive in 31 cases and negative in 50. There were 167 negative stone cultures, and in these cases, gram stain was positive in 5 and negative in 162. The calculated sensitivity and specificity of stone gram stain were 38% and 97%. The positive and negative predictive values were 86% and 76%, respectively. In the subset of 16 patients with positive stone fungal cultures, fungal smear was performed in 12 and was positive in 4, giving fungal smear a sensitivity of 33%. CONCLUSION: The results of this study suggest that stone gram stain cannot be relied on to detect a positive stone culture and may fail to detect up to 62% of infected stones. However, when positive, gram stain accurately predicts a positive stone culture in 86% of cases.
Authors: Daniel A Wollin; Adrian D Joyce; Mantu Gupta; Michael Y C Wong; Pilar Laguna; Stavros Gravas; Jorge Gutierrez; Luigi Cormio; Kunjie Wang; Glenn M Preminger Journal: World J Urol Date: 2017-02-03 Impact factor: 4.226
Authors: Mayandi Sivaguru; Jessica J Saw; Elena M Wilson; John C Lieske; Amy E Krambeck; James C Williams; Michael F Romero; Kyle W Fouke; Matthew W Curtis; Jamie L Kear-Scott; Nicholas Chia; Bruce W Fouke Journal: Nat Rev Urol Date: 2021-05-24 Impact factor: 14.432