The significance of stone culture in the incidence of sepsis. Results from a prospective, multicenter study on Infections post Flexible UreteroreNescopy (I-FUN) and laser lithotripsy for renal stones

: Objective Sepsis is the most serious complication of flexible ureteroscopy (F-URS) and laser lithotripsy. We assessed the influence of positive stone culture (SC) on major infectious complications (sepsis, septic shock). Methods This prospective study enrolled adult patients deemed suitable for F-URS and laser lithotripsy from 9 centers (January 2022-August 2023). Inclusion criteria: kidney stone(s); preoperative mid-stream urine culture (MSU); stone(s) assessed at CT scan; SC. Exclusion criteria: bilateral procedures; ureteral stones; children. Group 1: patients with sterile SC. Group 2: patients with positive SC. Data are presented as median (interquartile range). A multivariable logistic regression analysis was performed to evaluate factors associated with having a positive SC. Results 293 were included. Median age was 51.0 (24) years. There were 167 (57.0%) males. Group 2 included 32 (2.5%) patients. Group 2 patients were significantly older [75.0 (14) vs 51.0 (23) years, p=0.02]. Stone features were similar. Major infectious complications were higher in Group 2 (15.6% vs 0.4%). One patient died due to sepsis in Group 2. 2/6 (33.3%) of patients with major infectious complications had the same pathogen in MSUC and SC. At multivariable regression analysis, diabetes (OR 3.23), symptomatic urinary infections within 3 months before surgery (OR 4.82), and preoperative stent/nephrostomy (OR 2.92) were factors significantly associated with higher odds of positive SC. Conclusions Patients with positive SC have a higher incidence of major infectious complications following F-URS lithotripsy. SC should be performed whenever feasible being a poor pathogen correlation between MSUC and SC.