Research Of Resistance And Formation Mechanisms In Bacterial Biofilm

1. Research of the clinical distribution and drug resistance characteristic of biofilm bacteria in urinary tract infectionBackgroud:Biofilm refers to membrane-like bacteria cluster, which attached to inert objects such as bio-medical materials and mucosal, formed by bacterial reproduction , differentiation , and secretion of some polysaccharide matrix. Biofilm bacteria could escape the killing effects of antibiotics and organism immune system, and became a potential infection source which resulted to recurrent infection. The complicated drug-resistance mechanism of bioflim bacteria played an important role in the hospital onset of infection. In order to provide a reasonable guidance for clinical medication, this study focused on the research of clinical and drug-resistance characteristics of biofilm bacteria in UTI.Objective:This study was to screening biofilm bacteria in UTI, and to discussits drug-resistance characteristics by comparing the antibioticssensitivity between biofilm bacteria and planktonic ones.Material and methods:(1) Identification and clinical distribution of biofilm bacteria in UTI:From October 2007 to June 2008, 120 cases catheter and urine specimens from catheter-related UTI were collected from Third Xiangya Hospital. In order to understand the the clinical distribution of biofilm bacteria, poloxamer medium was used to identify biofilm bacteriaand 96 pore plate was used for semi-quantitative detection of biofilm bacteria.(2) Analysis the drug-resistance:Drug-sensitivity test was detected between biofilm and planktonic strains. And drug-sensitivity test of biofilm strain was compared in Poloxamer (Poloxamer, F-127) medium and MH medium.Results:(1)40%(48/120) strains were screen as biofilm. 43.75% (15/48) of the biofilm bacteria were Gram-positive Staphylococcus, 31.25% (21/48) were Enterococcus, and the rest were Gram-negative bacteria.(2) There is no significant difference of antibiotics sensitivity on MH medium between biofilm and planktonic bacteria. It showed significant difference of biofilm bacteria drug-resistance between Poloxamer and MH medium, and Poloxamer seemed to induce the resistance.ConclusionStaphylococcus and Enterococcus were the main biofilm bacteria of UTI in our hospital. Poloxamer medium could induce the drug-resistance which was similar to the situation in vivo. 2. Reach of Enterococcus faecalis-related genes, Quorum sensingsystem and biofilm formationBackgroundEnterococcus faecalis has been rising for the pathogens of nosocomial infection in the third place, easy to form biofilm, research-related genes in Enterococcus biofilm formation and its relationship; density sensor system (Quorum sensing, QS) regulation on the role of these genes, in turn affect the formation of biofilm on the search for a QS system to control biofilm Enterococcus pathway, in-depth identification of viable drug targets and small molecule substances to inhibit biofilm formation. It is great guiding significance for us to solve real clinical problems .Objective:To analyse the correlation between genes related Enterococcus faecalis (surface protein-Esp, the gene encoding gelatinase-gelE, fimbriae operon ebpA), virulence regulation and control devices - fsr system and biofilm formation. exploreing the differences in gene expression Of biofilm formation between the laboratory in vitro and in vivo.in order to provide a theoretical data for researching the QS system pathway to control biofilm formation in Enterococcus .Material and methods:(1)To use reverse transcription-PCR and real-time quantitative PCR method detecting the gene expression of esp, ebpA, gelE, fsrB in biofilm and planktonic bacteria group.(2) laboratory-induced biofilm formation in Enterococcus faecalis, real-time fluorescence quantitative PCR method detected the differences of expression in these genes before and after induction. Analysis gene expression differences of Enterococcus faecalis between laboratory-induced and clinical biofilm formation in vivo.Results:(1) esp, ebpA, gelE, fsrB genes are closely related to biofilm formation of enterococcus faecalis. Compared with planktonic bacteria, biofilm bacteria group esp, ebpA expression are 298.2 and 59 of its times that esp, ebpA can promote biofilm-forming. And, gelE, fsrB's are 1/243.9 and 1 / 249, which prompt to inhibit biofilm-forming.(2) In the process of biofilm-forming, fsr system can regulate the expression of gelE, and increased its expression. Speculating to adjust esp, ebpA gene expression, and enable them to reduce.(3)They are similar to the expression of esp, ebpA, gelE, fsrB between laboratory in vitro and in vivo about biofilm-forming, but the rate of changes smaller than in body form . Laboratory simulation of conditions that can hardly reflect the complex extracellular environment to form biofilm. Conclusions:esp, ebpA, gelE, fsrB genes are closely related to biofilm formation of enterococcus faecalis . esp, ebpA can promote biofilm-forming, and gelE, fsrB can inhibit biofilm-forming. Fsr system can regulate the expression of esp, ebpA and gelE, that reducing esp, ebpA and increasing gelE. At present, laboratory simulation of conditions that can hardly reflect the complex extracellular environment to form biofilm.