(HealthDay News) — For patients undergoing percutaneous stone removal, preoperative urine culture does not predict intraoperative stone culture results, according to a study published in the September issue of The Journal of Urology.

Jessica E. Paonessa, MD, from the Syracuse University School of Medicine in New York, and colleagues examined the correlation between urine and stone cultures in a cohort of 776 patients treated with percutaneous nephrolithotomy.

The researchers found that 45.4% of patients had positive preoperative urine cultures and 38.7% had positive stone cultures. Overall, 9.7% of patients had negative preoperative cultures and positive stone cultures; in 13.3% of patients with both cultures positive, the organism differed. In preoperative urine and stone cultures, gram-positive organisms predominated.

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“Preoperative urine cultures in patients undergoing percutaneous nephrolithotomy are unreliable as there is a discordance with intraoperative stone cultures in almost a quarter of cases,” the authors write. “There has been a notable shift toward gram-positive organisms in this cohort of patients.”


1. Paonessa JE, Gnessin E, Bhojani N, Williams Jr. JC, and Lingeman JE. Preoperative Bladder Urine Culture as a Predictor of Intraoperative Stone Culture Results: Clinical Implications and Relationship to Stone Composition. J Urol. doi:10.1016/j.juro.2016.03.148.