| BackgroundRecently, hospital-acquired infection has been a salient question in the clinicalwork. Widespread use of the medical implants in people’s body is one of its reasons.The morbidity of urinary tract infection is second only to respiractory systeminfections. The urinary tract infection is the most common infections in hospitals.The major risk factors which caused the urinary tract infections are as follows:indwelling catheters, people with low immunity and the using broad-spectrumantibiotics in abundance. The most common hospital-acquired infections areCAUTIs (catheter-associated urinary tract infections) which are maily caused byindwelling catheter in the bodies.The infection rate is increased with the timeprolonged of indwelling catheter. The reasons are as follows: on the one hand, thegradually increasies in antimicrobial resistant characteristics of pathogenic bacteriaare caused by long-term abusing the clinical antibacterial drugs, on the other hand,because of the existence of bacteria biofilm, bacteria which are inside of the biofilmcan escape the killing action of antibiotics and the clearing effects of body’simmune system. The bacteria biofilm is the potential source of infection and causesrecurrent attacks of various infections. Biofilm bacteria play a significant role innosocomial infection and make difficult therapy in clinical work. Consequently, it isof crucial importance to provide a more reasonable guidance for clinical medication in order to prevent and cure urinary tract infection, this study focused on theresearch of clinical distribution and drug-resistance characteristics of bacteria inindwelling catheter．Preious studies had confirmed that Enterococcus faecalis has been rising up tothe third place in pathogens which caused nosocomial infections, easy to formbiofilm. Therefore, researching related genes in Enterococcus biofilm formation andits relationship, quorum sensing system(Quorum sensing, QS)regulation on the roleof these genes，in turn affect the formation of biofilm on the search for the QSsystem to control the pathway of biofilm Enterococcus, in-depth identification ofthe viable drug targets and small molecule substances to inhibit biofilm formation．It is of great guiding significance for us to solve the real clinical problems．ObjectiveTo discuss the clinical distribution, we adopted the methods of cultivating,separating, purifying and identifying the bacteria in catheter-associated urinary tractinfection and then screening out biofilm bacteria and their corresponding planktonicbacteria. In order to investigate the drug-resistance characteristics of catheter-associated planktonic bacteria and biofilm ones in further study, we analyzed thedrug-resistance diversities by comparing the antibiotics sensitivity betweencatheter-associated planktonic bacteria and biofilm ones.To provide a theoretical data for researching the QS system pathway andcontrol biofilm formation in Enterococcus faecalis, we explored the correlationbetween related genes of the biofilm bacteria—Enterococcus faecalis we screenedout and the biofilm formation.The three target genes are the encoding gelatinasegene gelE, fimbriae operon ebpA, gene fsrB of virulence regulation and controldevices-fsr system.MethodsFrom October2011to May2012,418cases of indwelling catheter specimensfrom the patients who indwelled the catheter in urology of Dali University AffiliatedHospital of Yunnan Province were collected. In order to understand the the clinical distribution of the biofilm bacteria and its corresponding planktonic ones incatheter-associated urinary tract infection, all of the bacteria mentioned above werecultivated, separated, purified, screened and identified. Then96pore plates wereused for semi-quantitative detection of biofilm bacteria．The biofilm bacteria and their corresponding planktonic bacteria from the samecase by means of screening and identifying mentioned above were divided into twogroups—biofilm bacterial group and planktonic bacterial group.Drug-sensitivitytest was detected between the two groups in MH medium and then drug-sensitivitytest of biofilm bacteria were compared in MH medium and Poloxamer(Poloxamer，F-127)medium.Their differences of drug-resistant characteristics were analyzed bystatistical methods.PCR technology was used to detect and amplificate the expressions of the threerelated target genes: gelE, ebpA and fsrB in planktonic Enterococcus faecalis andtheir corresponding biofilm ones. Then we analyzed the expression quantities andrelationship among the three genes by using the SPSS11.0statistical software.Results219cases were infected in the418cases indwelling catheter specimens fromthe patients who indwelled the catheter in urology of Dali University AffiliatedHospital in Yunnan Province. The infection rate was52.39%.410strains of bacteriawere isolated, in which377strains were screened as planktonic strains.243strainsof the planktonic bacteria were Gram-positive ones and134strains wereGram-negative bacteria.43.21%(105/243) of the Gram-positive bacteria wereStaphylococcus and41.15%(100/243) were Enterococcus，which were in the largemajority.The rest134Gram-negative bacterial strains were only accounted for35.54%(134/377) of the total planktonic strains, including Escherichia coli,Pseudomonas aeruginosa and Acinetobacter baumannii.33strains were screened asthe biofilm ones, which were all Gram-positive microbes.There were no significant differences of the drug-sensitivity test results of17kinds of antibiotics we tried on MH medium between the biofilm bacterial group of 33strains and the corresponding planktonic group(P>0.05). However, it showedsignificant differences of biofilm bacterial drug-resistance results between MHmedium and poloxamer medium(P<0.05), There were no significant statisticaldifferences of antibiotics sensitivity between doxycycline(DX) and cefoxitin (FOX)(P>0.05).Poloxamer seemed to induce the resistance．There were21strains of Enterococcus faecalis in the biofilm group screenedout, we detected the expression of genes gelE, ebpA and fsrB respectively, and theresults showed that their positive rates were9.52%(2/21),95.24%(20/21) and9.52%(2/21)，in the corresponding planktonic group they were85.71%(18/21),9.52%(2/21) and90.48%(19/21). Compared with planktonic bacteria, positiveexpression of genes gelE, ebpA and fsrB in biofilm bacteria group respectively were0.111(2/18)，10(20/2) and0.105(2/19) of their times，which prompted that ebpA，gelE and fsrB are closely related to biofilm formation of Enterococcus faecalis:ebpAcan promote biofilm-forming but gelE and fsrB can inhibit biofilm-forming．ConclusionStaphylococcus, Enterococcus and Escherichia coli were the main planktonicbacteria in catheter-associated urinary tract infection in our hospital．Staphylococcusand Enterococcus were the main biofilm bacteria. There were no significantdifferences of antibiotics sensitivity in vitro between the biofilm bacteria and theircorresponding planktonic ones. However, there were significant differences ofantibiotics sensitivity in vitro among the biofilm bacteria group between theordinary MH medium and the poloxamer medium.We suggested that the poloxamermedium could induce the drug-resistance which was similar to the situation in vivo.ebpA, gelE and fsrB genes are closely related to biofilm formation ofEnterococcus faecalis. Gene ebpA can promote biofilm-forming, and gelE and fsrBcan inhibit biofilm-forming．... |
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