Effects Of RNAⅢ-inhibiting Peptide(RIP) On Staphylococcus Aureus Adhesion And Biofilm Formation In Early Stage

BackgroundAt present,artificial joint replacement has become the most effective method for the treatment of end-stage bone and joint diseases,but the number of surgery is increasing year by year,and the number of serious complications of prosthetic joint infection(PJI)is increasing.Staphylococcus aureus is a common pathogen of PJI,such as drug resistant Staphylococcus aureus,which is a major clinical problem.At present,surgical debridement combined with long term antibiotic treatment is considered to be the main method for the treatment of PJI.Even so,the recurrence of infection is still possible after the operation,and the most likely cause of the recurrence is the existence of bacterial biofilm.When bacteria adhere to the surface of the body,bacteria can gather together by secreting mucopolysaccharide and other substances,and further proliferate and proliferate,eventually forming a biofilm with a barrier effect.The barrier effect of biofilm effectively hinders the killing effect of antimicrobial agents on membrane deep bacteria.In clinical,the bacterial resistance to antibiotics is caused by the protective effect of biofilm to bacteria.Once the infection forms the biofilm around the prosthesis,it is difficult to kill the pathogenic bacteria.If we can reduce the formation of bacterial biofilms,we can not only lose the ability of bacterial adhesion and aggregation,but also greatly reduce the drug resistance of bacteria.In recent years,Quorum sensing(QS)can regulate biofilm formation through the relationship between the density of bacterial colonies and the surrounding environment to regulate biofilm formation.It has been shown that the RNAIII-inhibiting peptide(RIP)produced by coagulase negative Staphylococcus can interfere with the quorum sensing system and thus inhibit the bacterial biofilm.Therefore,the study of the effect of RNAIII-inhibiting peptide(RIP)on the adhesion and biofilm formation of Staphylococcus aureus has important clinical guiding significance for the prevention and control of PJI.ObjectiveTo observe the effect of RNAIII-inhibiting peptide(RIP)on the adhesion and early biofilm formation of Staphylococcus aureus,and to provide new ideas and methods for the clinical diagnosis and treatment of periprosthetic infection.Methods(1)The strains of Staphylococcus aureus in Guangzhou No.1 People’s Hospital were collected and screened by Congo red experiment and crystal violet semi quantitative experiment,the strains with the strongest production membrane were selected as experimental strains(2)The biofilm model of Staphylococcus aureus in vitro was established by the slide method,and the formation of the biofilm of the experimental strains after 1,3,6,12,24 and 48 hours was observed.(3)The effects of different concentrations of RIP on the biofilm production ability of the experimental strains were detected by microplate culture and crystal violet semi quantitative method.(4)The effect of RIP on the adherence of the experimental strains was observed by fluorescence staining.(5)The expression of biofilm associated genes(icaA,icaR,fnbA,atlA and sarA)in the experimental group and the control group were detected by real-time fluorescence quantitative PCR Results(1)Staphylococcus aureus strain 27929 screened the most productive biofilm,and was identified as an experimental strain.(2)A Staphylococcus aureus biofilm in vitro model was established.The density of bacteria in the biofilm increased over time within 48 hours..(3)the biofilm production ability of Staphylococcus aureus in experimental group decreased with the increase of RIP concentration,and the biofilm production ability of 250ug/ml RIP was the lowest..(4)The number of bacteria labeled with fluorescent staining on the surface of the object was observed.And the number of bacteria labeled in the experimental group was significantly less than that in the control group.(5)The number of icaA,fnbA and atlA in the experimental group was lower than that of the control group(P < 0.05),and the number of icaR expressed in the experimental group was higher than that of the control group(P < 0.05).There was no significant difference in the expression of sarA in the experimental group and the control group(P < 0.05).Conclusion1 RIP inhibite the adhesion of Staphylococcus aureus and the formation of early biofilm in vitro.2 RIP play a regulatory role in the expression of some genes related to the adhesion and biofilm formation of Staphylococcus aureus.