Infectious Complications After Laser Vaporization of Urinary Stones During Retrograde Intrarenal Surgery Are Not Associated With Spreading of Bacteria Into Irrigation Fluid but With Previous Use of Fluoroquinolones

Background: The pathogenesis of infectious complications after retrograde intrarenal surgery (RIRS) is not fully understood. Objective: To evaluate spreading of bacteria into irrigation fluid and blood during RIRS for stone management and to correlate such spreading with infectious complications. Design, setting, and participants: From January to December 2017, 38 patients who underwent RIRS for stones in two urological units were enrolled in this prospective, longitudinal cohort study. Intervention: A urine culture was taken before surgery and antimicrobial prophylaxis was given in line with the European Association of Urology guidelines. Blood and irrigation fluid samples were collected at the start of the endoscopic procedure and every 30min during the procedure. All samples were microbiologically examined and findings were compared with clinical data. Outcome measurements and statistical analyses: Symptomatic and asymptomatic urinary tract infectious complications were correlated with microbiological and clinical data, using Student t test or Mann-Whitney U test. Results and limitations: Ten patients showed significant bacterial growth in irrigation fluid samples (seven Escherichia coli, two Klebsiella pneumoniae, and one Pseudomonas aeruginosa). Eight patients (21%) got febrile urinary tract infections during hospital stay: two had bacterial growth in the irrigation fluid (25%) and one also had bacteremia (12.5%). No correlation was found either between the bacterial growth in the irrigation fluid samples and the urine cultures that were taken before the procedure, or between the bacterial growth in the irrigation fluid samples and the development of postoperative infectious complications. Previous use of fluoroquinolones and a history of urinary tract infections were associated with infectious complications after RIRS. Conclusions: We demonstrated spreading of bacteria into the irrigation fluid during RIRS procedures, but this spreading was not associated with the development of infectious complications. Particular attention should be given to previous antibiotic treatment before administration of antimicrobial prophylaxis.