For reliable urine cultures in the detection of complicated urinary tract infection, do we use urine specimens obtained with urethral catheter or a nephrostomy tube?

Objective: The aim of this study was to compare the results of urine cultures obtained either from urethral, and percutaneous nephrostomy (PCN) catheters. Materials and methods: This study included 328 consecutive patients that underwent PCN at our institution with complicated urinary tract infections (UTIs) between July 2010 and April 2015. Results of urine cultures obtained from the urethral and nephrostomy catheters were compared. Results: This study included 152 male and 176 female patients. Mean age of the patients was 46.2 +/- 24.3 years. The main indications were obstructive uropathy due to urolithiasis complicated with pyonephrosis 145 (44%), malignant disease (n=87; 26%), pregnancy (n=26; 8%), and anatomical abnormality (n=23; 7%). One hundred and twenty three patients had diabetes mellitus. The most common causative organisms were Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Blood cultures showed the same results for the PCN and bladder urine cultures. The bladder urine culture was positive in 304 patients, while the PCN urine culture in 314 patients. Conclusion: PCN is an important treatment for the management of pyonephrosis. Cultures from the PCN yield valuable information that is not available from urethral urine cultures, and is a guiding tool for antibiotic therapy selection.