The Eliminated Effect Of D-tyrosine Combined With Vancomycin On MRSA And Its Biofilm

Background At present,artificial joint replacement is the most effective therapy for end-stage joint disorders and improving the knee function.The number of patients with prosthetic joint infection(PJI)is increasing due to the increasing amount of artificial joint replacement surgery.Among them,a huge obstacle was infected by methicillin-resistant staphylococcus aureus(MRSA).Although,two-stage revision operation combined with vancomycin has been recognized as gold-standard therapy for prosthetic joint infection by MRSA,there still has a possibility of infection relapse which due to bacteria biofilm.Bacterial biofilm was formed by glycosaminoglycan which was secreted by bacterial after attaching on the object surface.The function of bacterial biofilm was conglutinating the bacterial,protecting them from antibiotics killing through the biofilm barrier and contributing the proliferation and resistance of bacterial.If biofilm can't be eliminated thoroughly,recurrence of PJI will be inevitable.Therefore,this phenomenon has been attracted high attention in clinical.Recently,some study reported that have D-amino acid can scatter bacterial biofilm,with the strongest effect of D-tyrosine.So,exploringthe method to eliminate MASA and its biofilm show important clinical significance.Objective To affirm the feasibility and superiority of ELT used in early postoperative infection after TKA and explore its possible molecular mechanism of resistance infection.Method(1)We collected clinical MRSA strains from Guangzhou First People's Hospital and established the biofilm models by plate cultivation method.And thenwe selected a targeted strain with a strongest capacity to form biofilm through a semi-quantitative method of crystal violet dyeing.(2)After successfully establishing MASA biofilm using the targeted strain,they were divided into 4groups,control group,D-tyrosine group,vancomycin group,and united group.After specific intervention,the change of MASA and its biofilm were checked by the staining of crystal violetand fluorescence,using high magnification microscope and confocal laser scanning microscope respectively,at several time points of 1h,6h,12 h and 24 h.Result(1)MRSA29213 was confirmed as the targeted strain which has the strongest capacity to form biofilm.(2)With time going on,bacterial density decreased in treatment group compared with control group with D-tyrosine group and united group obviously.There was statistically significant difference between each group(P<0.05).(3)Laser scanning confocal microscope result showed the number of dead bacterial increased with time going in vancomycin group and united group before 12 h,when compared with D-tyrosine groupand control group,with the united group most impressive.There was statistically significant difference between vancomycin group and united group(P<0.05).After 12 h,there was not obvious change invancomycin group,and the number of dead bacterial still increased.Conclusion D-tyrosine can scatter MRSA biofilm in vitro;Combination D-tyrosine with vancomycin has an advantage on eliminating MRSA and its biofilm.