The Analysis of the autoinducer gene expression related quorum sensing mechanism in catheter associated urinary tract infection

Purpose: Catheter associated urinary tract infection (CAUTI) frequently occurs in the patients with an indwelling Foley catheter, and it can cause serious morbidity or mortality. However, there have been no reports about quorum sensing mechanisms in indwelling Foley catheter. It's our purpose to find out the quorum sensing mechanisms of isolated bacteria from biofilm in Foley catheters. Materials and Methods: Silicone Foley catheters were placed in 90 patients with neurogenic bladders. At the 3rd, 5th, 7th, 14th and 30th day after the catheters were placed, the catheters were removed and the biofilm formations were evaluated by routine culture and microscopy. The ygaG gene, which was reported to be an autoinducer synthase gene was carried out cloning in E. coli. The quantity of the mRNA expression of the ygaG gene was analyzed according to the time by competitive reverse transcription polymerase chain reaction (RT-PCR). Results: 289 different types of bacteria were isolated by cultivation. The most common species were Pseudomonas, Klebsiella, Serratia, Proteus and Escherichia species. The autoinducer synthase gene, such as the ygaG gene for Escherichia coli, was detected by RT-PCR. On competitive RT-PCR of the ygaG gene, the mRNA expression was 3.77×10⁹ copies/μl at the 3rd day, 5.94×10⁷ copies/μl at the 5th day, 8.07×10⁷ copies/μl at the 7th day, 2.51×10⁶ copies/μl at the 14th day and 6.81×10⁸ copies/μl at the 30th day. Therefore, the expression of the autoinducer synthase gene was observed at the early insertion period and it was then maintained. Conclusions: This is the first study to document the autoinducer synthase gene expression associated quorum sensing mechanism in CAUTI. The quorum sensing mechanism may be a new target for the management of CAUTI.