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

Abstract

IntroductionThe aim of the trial was to estimate the relationship between colonization of the Double–J catheter, and the microorganisms cultured from urine.Material and methods60 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.ResultsUrine 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.ConclusionsDouble–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.

Molecular Techniques Complement Culture-Based Assessment of Bacteria Composition in Mixed Biofilms of Urinary Tract Catheter-Related Samples

“…Though DJCU culture positivity rate could seem low, it corresponds to other authors' results. Farsi et al ( 1995 ) detected 29.9%, Paick et al ( 2003 ) 21%, and Kliś et al ( 2014 ) just 13% positive urine cultures.…”

“…Our results, showing a higher positivity rate of DJC sonication fluids captured by PCR-DGGE than by culture (91.7 vs. 78.3%), are consistent with other studies. Kliś et al ( 2014 ) even found 100% colonization incidence employing PCR-DGGE. Bonkat et al ( 2011 ), Paick et al ( 2003 ), and Farsi et al ( 1995 ) reported 36, 44, and 68% culture positivity rate in DJC sonicates, respectively.…”

“…This can be attributed to antibiotic prophylaxis in patients undergoing the stent replacement, easily affecting the planktonic bacterial cell viability in urine samples, letting the viability of biofilm-embedded bacteria unaffected, at the same time. Moreover, device colonization is not necessarily manifested by bacteriuria (Paick et al, 2003 ; Xu et al, 2012 ; Ozgur et al, 2013 ), especially when Gram-positive colonizers are present (Kliś et al, 2014 ). On the contrary, it could not be explained simply by the presence of fastidious and uncommon bacteria in samples which would more likely be detected by the molecular method.…”

“…The bacterial composition of colonizing biofilm is affected by various factors such as indwelling time, sex, comorbidities, or patient conditions (Paick et al, 2003 ; Frank et al, 2009 ; Xu et al, 2012 ; Kliś et al, 2014 ). Gram-negative rods predominate on urinary catheters, while gram-positive cocci prevail on stents (Paick et al, 2003 ; Frank et al, 2009 ; Holá et al, 2010 ; Bonkat et al, 2011 , 2012b , 2013 ; Choe et al, 2012 ; Xu et al, 2012 ; Kliś et al, 2014 ). Routine urine culture provides valuable quantitative information enabling us to distinguish between contamination/colonization and aetiological agents (Hooton et al, 2010 ), but results can be negatively influenced by known culture pitfalls.…”

“…Taxonomical characterization of separated amplicons is usually required in clinical samples and is possible by Sanger sequencing (Choe et al, 2012 ), alternatively in combination with chromatogram software separation by RipSeq Mixed tool (Kotásková et al, 2017 ). DGGE has been applied to different clinical materials (Davies et al, 2004 ; Li et al, 2005 ; Liu et al, 2015 ), but rarely to urinary catheter (Frank et al, 2009 ; Choe et al, 2012 ; Xu et al, 2012 ) or ureteral stents (Kliś et al, 2014 ). Modern Next-Generation Sequencing (NGS) techniques could be beneficial in studying highly diverse bacterial communities and/or in high-throughput study designs.…”