Rate of positive urine culture and double-J catheters colonization on the basis of microorganism DNA analysis

Introduction The aim of the trial was to estimate the relationship between colonization of the Double-J catheter, and the microorganisms cultured from urine. Material and methods 60 patients, who had Double-J catheters inserted, participated in the study. All the subjects had their midstream urine samples taken prior to the stent insertion and removal. A negative urine culture before catheterization was mandatory to participate in the study. The patients were assigned into three subgroups, according to stenting duration: 1) 20 to 30 days (18 cases); 2) 30 to 90 days (30 cases); 3) longer than 90 days (12 cases). Bacterial and fungal DNA was identified using electrophoresis in polyacrylamide gel with a denaturing gradient (PCR-DGGE). The relationship between the genetic analysis of the catheter and the urine culture was estimated. Results Urine cultures were positive in only 8 patients, while Double-J catheter analyses were positive in all cases. In 2 cases one type of microorganism was isolated from the stent surface while the remaining 58 catheters were colonized by more than one pathogen. In three cases fungi were isolated. There were only three types of pathogens cultured from urine specimens. Urine and stent cultures were consistent in 5 cases. In 3 cases urine culture and stent analysis were not consistent. Conclusions Double-J catheter retention in the urinary tract is associated with an extremely high risk of bacterial colonization, while the risk of urine infection is about 8-fold lower. There is a great inconsistency between urine infection and catheter colonization, indicating a low predictive value of urine culture for estimating stent colonization.