# Unravelling the Added Value of Urinary Stone Cultures Towards Infectious Complications Following Treatment of Renal Stones

## TL;DR

This study shows that positive urinary stone cultures are linked to higher infection risks after kidney stone surgery, with E. coli being a common cause.

## Contribution

The study identifies pre-operative factors associated with infected stones and highlights antibiotic resistance in cultured bacteria.

## Key findings

- 16 out of 126 patients had positive stone cultures, showing a 12.6% infection rate.
- E. coli was the dominant bacteria in both urine and stone cultures.
- Pre-operative factors like chronic kidney disease and stone volume were significantly associated with positive cultures.

## Abstract

Aim: To explore the association between urinary stone cultures and infectious complications following PCNL. Materials and Methods: An observational case–control study was conducted in patients undergoing PCNL. The assessment included demographic parameters, medical history, urinalysis, and urine culture and blood testing. Pre-operatively, urinary stone samples were collected for cultures. Post-operatively, patients were observed for infectious complications such as fever and/or SIRS. Patients were divided into two groups based on the presence or absence of infected renal calculi. Patient characteristics, stone factors, and intra-operative and post-operative findings were studied in relation to stone culture. Descriptive statistics was used to present the data and the SPSS software was used for analysis. Results: From December 2023 to March 2025, a total of 126 patients were included in the study. A total of 16 patients (12.6%) had a positive stone culture. Statistical significance was found upon the comparison of stone culture with gender (p = 0.046), chronic kidney disease (p = 0.002), pre-operative urine culture (p = 0.001), pre-operative haemoglobin (g/dL) (<0.001), pre-operative S. creatinine (mg/dL) (p = 0.038), stone volume (mm3) (p = 0.012), CROES score (p = 0.023), SIRS (p = 0.001), and AKI (p = 0.021). Conclusions: Infected renal calculi identified by positive stone cultures were strongly associated with infective complications such as fever and SIRS following PCNL. E. Coli was the dominant bacteria present in both bladder urine and renal stone culture. The occurrence of infectious complications despite the administration of pre-operative antibiotics highlights the antibiotic resistance patterns noted among the cultured bacteria. The pre-operative factors identified to be associated with a positive stone culture could potentially be used for predicting infected stones, thereby improving outcomes.