Evaluation of the bacterial distribution within the biofilm by denaturing gradient gel electrophoresis in the rat model of urinary catheters

Purpose: Most nosocomial urinary tract infections are related to urinary catheters and their biofilm. For the research in this province, animal models are needed to explain the host-pathogen interactions and have an advantage in controlling external interference. This study investigated the validity of the denaturing gradient gel electrophoresis (DGGE) technique for identification of bacteria in a rat model of urinary catheter biofilm. Methods: After cutting with aseptic technique, the 24-gauge polyurethane IV catheter was placed in the female rat bladder through the urethra. The catheters were kept in the bladder for 2, 4, or 6 weeks for each group. The genomic DNA was isolated from harvested biofilm of the extracted catheter, and DGGE was performed. The band patterns of DGGE results were analysed, and the sequences were compared using the BLAST from the NCBI. Results: The results show that Pseudomonas aerusinosa, Escherichia coli, Enterococcus spp., and Corynebacterium sp. were the dominant bacterial species, regardless of the indwelling periods, and other species of bacteria, including Burkholderia and Achromobacter, were identified. The changes in bacterial distribution for the different indwelling periods were non-specific. Conclusions: This study using rat model of urinary catheter suggests that DGGE is a useful method in the analysis of the bacterial community in biofilms. Molecular techniques, including DGGE, are valuable to identify fastidious bacteria in the urinary catheter biofilm. This study may be used as fundamental data for studies involving human materials hereafter.