Influence of biofilms on morbidity associated with short-term indwelling ureteral stents: a prospective observational study

PURPOSE
To evaluate the influence of biofilms on morbidity associated with short-term ureteral stenting using contemporary methods of biofilm examination and validated assessment of symptoms.

METHODS
Patients undergoing temporary ureteral stenting for secondary ureterorenoscopy due to urinary calculi were prospectively included. The German Ureteral Stent Symptoms Questionnaire (USSQ) was used to assess stent-associated morbidity. Biofilms were removed from stents using 'pinhole extraction', a novel, validated, abrasion-based technique. Extracted biofilms were analyzed for total mass, bacterial load and mineral components. Correlation between total biofilm mass and USSQ total score was the primary outcome variable analyzed using Spearman correlation. Secondary outcomes included correlations between various biofilm characteristics and symptoms.

RESULTS
94 patients were included in the analysis. Extracted biofilm mass had a median of 37.0 mg (0-310.2 mg) per stent. No correlation between total biofilm mass and USSQ total score was found (Spearman r = 0.012; p = 0.911). Correlations between biofilm characteristics and morbidity were generally weak and not significant. Significant correlations could be found between biofilm mass and hematuria (r = 0.280; p = 0.007), and between the number of bacteria (qPCR) and the USSQ subscore for pain (r = 0.243; p = 0.019) and the intake of analgesics (r = 0.259; p = 0.012).