Effect Of Enterococcus Faecalis Endocarditisantigen EfaA On The Rat Endocarditis

Objectives : Further research of the role of Entrococcus faecalis endocarditis antigen(Efa A) in rats infective endocarditis, pave the way for further study of prevention and cure of patients from Entrococcus faecalis infective endocarditis.Methods:One:Establishment and evaluation of rat model of endocarditisAccording to the method of the right carotid arterial catheterization the rat model of Entrococcus faecalis endocarditis is established. Polyethylene tubing(PE-50)passed within the right carotid artery into the left ventricle. A volume of 0.5 ml of an overnight culture of Entrococcus faecalis efa A+ strain(1×108CFU/ml)was injected through a tail vein 1 days after catheterization, rats were sacrificed by intraperitoneal injection 72 hours later, taking aortic valve vegetation in rats heart, comprehensively evaluate model is set up successfully by weighing vegetation wet weight, counting the number of colonies(CFU/g) were isolated of vegetation and aortic pathological HE staining.Two: Comparison of the role of Enterococcus faecalis strain efa A- and efa A+ transformed strain in the rat endocarditisRats were grouped firstly, according to the method of the right carotid arterial catheterization the rat model of Entrococcus faecalis endocarditis is established. A volume of 0.5 ml(1×108CFU/ml) of an overnight culture of Entrococcus faecalis efa A- strains and efa A+ strain were respectively injected through a tail vein 1 days after catheterization, Rats were sacrificed by intraperitoneal injection 72 hours later, taking aortic valve vegetation in rats heart, weighing; Counting bacteria(CFU/g) after homogenizing; Inflammation was observed by aortic HE staining.Three: Comparison the rat mortality of Enterococcus faecalis strain efa A- and efa A+ transformed strain in the rat endocarditisRats were grouped firstly, according to the method of the right carotid arterial catheterization the rat model of Entrococcus faecalis endocarditis is established. A volume of 0.5 ml(1×108CFU/ml) of an overnight culture of Entrococcus faecalis efa A- strains and efa A+ strain were respectively injected through a tail vein 1 days after catheterization, observe the number of dead rats every day.Four: Comparison of Drug sensitive test of the vegetation in IE of Enterococcus faecalis strain efa A- and efa A+ transformed strainEntrococcus faecalis efa A+ strain drug sensitive test through Kirby-Bauer disk diffusion method. We choice penicillin and measure its MBC according to inhibition zone diameter. Respectively taking aortic valve vegetation of Enterococcus faecalis strain efa A- and efa A+ transformed strain effected rats into NS with penicillin(160μg/ml) and NS and soaking 24 h, counting bacteria(CFU/g) after homogenizing.Results:1. Rat valve vegetation can be seen2. The efa A+ transformed strain group compared to wild group and blank control group, a higher mortality rate, vegetation is heavier, more bacteria count, more severe inflammation.3. 7 days mortality of blank control group and wild group is 30% and 40% respectively, transformed strain group is 70%, the rest of rats to be put to death 7 days later and we can observe different degrees of endocarditis4. The efa A+ transformant group, Live bacteria number of Penicillin treatment group and NS treatment group are 5.759×1010CFU/g、6.204×1010CFU/g respectively, the control group, Live bacteria number of Penicillin treatment group and NS treatment group are 1.058×1010CFU/g 、2.754×1010CFU/g respectively.Conclusions: 1.The rat model of Entrococcus faecalis endocarditis had been successfully established. 2. Entrococcus faecalis efa A antigens play a important role in rats infective endocarditis. 3. The biofilm in the IE causeed by efa A+ transformant is more compact and basically confirmed that efa A leading to the development of IE through contribute to the formation of biofilm.