A Comparison of Pre-operative Urine Culture with Intra-operative Stone Culture and Its Association with Post-procedural Sepsis: A Prospective Observational Study

Background and Aim: Urosepsis is a dreaded complication following endourological procedures. Urinary calculi are known to harbour bacteria that may be released into the circulation during fragmentation, potentially leading to urosepsis. Thus, urosepsis may develop despite a sterile pre-operative mid-stream urine (MSU) culture. Stone culture is not routinely performed in endourological practice. This study aimed to evaluate (i) the relationship between pre-operative MSU culture and intra-operative stone culture, and (ii) their association with postoperative urosepsis. Materials and Methods: In this comparative observational study (March 2023 – May 2024), 143 patients who underwent percutaneous nephrolithotomy, ureteroscopic lithotripsy, or cystolithotripsy were evaluated. Pre-operative MSU cultures and intra-operative stone cultures were obtained and analysed for positivity, bacterial spectrum, and stone location. Postoperatively, all patients were monitored for sepsis, defined by standard Systemic Inflammatory Response Syndrome (SIRS) criteria in the presence of infection. Results: MSU cultures were positive in 15 patients (10.5 %), whereas stone cultures were positive in 40 patients (28 %), a significantly higher rate (p = 0.03). Escherichia coli was the predominant pathogen in both MSU (73.3%) and stone cultures (50 %). Concordant growth was observed in only 4 of 55 cases (7.3%). Nine patients (6.3 %) developed postoperative sepsis: 7 of 40 with positive stone cultures versus 2 of 103 with negative stone cultures (p = 0.002). Pre-operative MSU culture status was not significantly associated with sepsis (p = 0.24). Conclusion: The microbiological profile of intra-operative stone cultures differs significantly from that of pre-operative MSU cultures. Stone culture is a better predictor of postoperative urosepsis and, when positive, may guide targeted antimicrobial therapy at minimal extra cost. Routine stone culture and sensitivity testing should therefore be incorporated into endourological stone surgery practices.