# Urinary Tract Infection in Patients with Urolithiasis: A Large Retrospective Observational Study of Clinical Features and Microbiological Spectrum

## TL;DR

This study shows that patients with kidney stones are more likely to get UTIs, with factors like high urine pH and prolonged stent use increasing infection risk.

## Contribution

The study identifies specific clinical and microbiological risk factors for UTIs in patients with urolithiasis using a large observational dataset.

## Key findings

- UTIs were more common in stone-forming patients (34.5%) compared to non-stone patients (28.9%).
- Elevated urine pH and hydronephrosis were independently associated with UTI in stone patients.
- Prolonged stent dwell time above 29.5 days increased UTI risk with moderate sensitivity and specificity.

## Abstract

Urinary tract infections (UTIs) and urolithiasis exhibit a complex bidirectional relationship in which microbial colonization and urinary obstruction may mutually reinforce each other. This retrospective observational study evaluated clinical and microbiological factors associated with UTI in patients with urolithiasis using a large institutional dataset. A total of 23,241 urine cultures obtained from 12,708 unique patients were analyzed, comparing individuals with and without urolithiasis. In stone-forming patients, demographic variables, urine pH, hydronephrosis, ureteral double J stent presence and indwelling duration, urinary anomalies, and stone characteristics were assessed. Logistic regression identified independent associations, and ROC analysis defined optimal risk thresholds. UTI were more frequent in the stone group (34.5%) compared with non-stone forming patients (28.9%, p < 0.001). Escherichia coli was the most common uropathogen overall, whereas Klebsiella pneumoniae, Enterococcus faecalis, and Pseudomonas aeruginosa were significantly enriched in patients with stones. Elevated urine pH (OR: 6.37; CI: 2.67–15.19; p = 0.001) and hydronephrosis (OR: 9.14; CI: 3.74–22.35; p = 0.001) were independently associated with UTI. A stent dwell time above 29.5 days was associated with infection with 85% sensitivity and 54% specificity (AUC: 0.70; CI: 0.68–0.73), and urine pH 6.2 or higher was associated with infection with 86% sensitivity and 67% specificity (AUC: 0.77; CI: 0.75–0.80). These findings underscore that urine alkalinity, obstruction, and prolonged stenting are key factors associated with infection risk, supporting the need for careful stent management and timely microbiological evaluation in patients with urolithiasis.