Stone and pelvic urine culture and sensitivity are better than bladder urine as predictors of urosepsis following percutaneous nephrolithotomy: A prospective clinical study

Purpose: Urosepsis due to manipulation during percutaneous nephrolithotomy (PCNL) can be catastrophic despite prophylactic antibiotic coverage, and negative midstream urine culture and sensitivity testing (C&S). It has been postulated that bacteria in the stone may be responsible for systemic infection. In this prospective study we determined the correlation between different sites of urine sampling, including stones, and also ascertained which is more predictive of urosepsis. Material and Methods: All patients undergoing PCNL who fulfilled our selection criteria were recruited. The samples collected were 1) midstream urine and bladder urine at cystoscopy, 2) renal pelvic urine collected at percutaneous puncture of the pelvicaliceal system and 3) extracted and later fragmented stones. They were sent immediately for C&S. Patients were monitored for systemic inflammatory response syndrome (SIRS). Results: A total of 54 procedures were suitable for analysis. Midstream urine C&S was positive in 11.1% of cases, stone C&S was positive in 35.2% and pelvic C&S was positive in 20.4% (p = 0.009). Pelvic urine C&S predicted infected stones better than bladder urine C&S. Of the patients 37% had SIRS and 3 experienced septic shock. Patients with infected stones or pelvic urine were found to be at a relative risk for urosepsis that was at least 4 times greater (p = 0.0009). Bladder urine did not predict SIRS. Stone C&S had the highest positive predictive value of 0.7. Preoperative hydronephrosis correlated with infected pelvic urine. No patients with urosepsis had positive blood C&S. Conclusions: The results of this study suggest that positive stone C&S and pelvic urine C&S are better predictors of potential urosepsis than bladder urine. Therefore, routine collection of these specimens is recommended.