Experiments On Periprosthetic Joint Infection In Diagnosis And Treatment Based On The Characteristics Of Bacterial Metabolic

Objective: Accurate and timely diagnosis and effective treatment of periprosthetic joint infection are still difficult problems.Firstly,the diagnostic efficacy of serum D-lactate,synovial D-lactate and other related markers for periprosthetic joint infection was explored.Then,to explore and construct the persisters model of periprosthetic joint infection,and explore the characteristics of persisters in vitro preliminarily.Lastly,to explore the effect of methylene blue-mediated sonodynamic therapy and pyropheophorbide-α-mediated photodynamic therapy on the clearance of staphylococcus and its biofilm.Methods: 1)Consecutive patients with preoperative blood and intraoperative joint aspiration of a prosthetic hip or knee joint before revision arthroplasty were prospectively included.The diagnosis of PJI was based on the criteria of the Musculoskeletal Infection Society,and the diagnostic values of markers were estimated based on receiver operating characteristic(ROC)curves by maximizing sensitivity and specificity using optimal cut of values.2)Consecutive patients with aspiration of intraoperative synovial fluid from patients undergoing periprosthetic joint infection and aseptic revision.Then,the synovial D-lactate,synovial white blood cell count and neutrophil ratio were detected and analyzed base on based on ROC curves by maximizing sensitivity and specificity using optimal cut of values.3)The performance of simulated synovial fluid(SSF)for bacterial culture was evaluated by the bacterial growth curve and biofilm formation.Sterilization curves were used to screen planktonic persisters and persisters in biofilm of staphylococcus.The bacterial metabolic activity was assessed by5-cyano2,3-diphenyltetrazolium.Using plate count to evaluate the efficacy of fructose in improving the bactericidal effect of gentamicin on persisters in biofilm.4)The bactericidal effect of sonodynamic therapy and photodynamic therapy on staphylococcus was evaluated by counting bacterial coating plates.The clearance effect of biofilm was evaluated by semi-quantitative crystal violet assay.Results: Of 52 patients,26 were diagnosed with PJI,and 26 were diagnosed with aseptic failure.ROC curves showed that serum D-lactate,fbrinogen(FIB)and erythrocyte sedimentation rate(ESR)had equal areas under the curve(AUCs)of 0.80,followed by D-dimer and fbrin degradation product,which had AUCs of 0.67 and 0.69,respectively.Serum D-lactate had the highest sensitivity of 88.46% at the optimal threshold of 1.14 mmol/L,followed by FIB and ESR,with sensitivities of 80.77% and 73.08%,respectively,while there were no significant differences in specificity(73.08%,73.08% and 76.92%,respectively).2)The area under the curve of synovial D-lactate,synovial white blood cell count and synovial neutrophil ratio were 0.87,0.80 and 0.88,respectively.The optimal cut-off value of synovial D-lactate was 1.56 mmol/L,the diagnostic sensitivity and specificity were 95.65% and68.00%,the sensitivity and specificity of the white blood cell count in the joint fluid were70.00% and 87.50%,and the sensitivity and specificity of the proportion of neutrophil were 80.00 and 100.00,respectively.3)SSF can effectively promote the growth of staphylococcus,while hyaluronic acid can inhibit the growth of staphylococcus and the formation of biofilm in a concentration dependent manner.For planktonic staphylococcus,using the concentration of ≤25 mg/L of vancomycin for 48 h can be used as a screening condition for persisters,while the concentration of ≥50 mg/L of vancomycin could kill staphylococcus faster.For staphylococcus in biofilm,the concentration of ≥25mg/L of vancomycin for 12 h could be used as a screening condition for persisters.Fructose could improve the bactericidal effect of gentamicin on persisters in biofilms.4)The experimental model of staphylococcus epidermidis biofilm was successfully constructed in vitro.Methylene blue-mediated sonodynamic therapy and photodynamic therapy can effectively remove staphylococcus epidermidis and its biofilm.Conclusion: The efficacy of serum D-lactate in the diagnosis of periprosthetic joint infection is similar to that of FIB and ESR.Serum D-lactate has the advantages of strong pathogen specificity,high sensitivity,minimally invasive,fast acquisition and preparation of serum,which can be used as a screening marker for periprosthetic joint infection.Compared with serum D-lactate,white blood cell count and neutrophil ratio in the joint fluid,the synovial vitro experimental model of PJI in persisters.And the planktonic staphylococcus could be eliminated faster by increasing the concentration of vancomycin.At the same time,adding fructose could enhance the bactericidal effect of gentamicin on persisters in biofilm.Methylene blue-mediated sonodynamic therapy and pyropheophorbide-α-mediated photodynamic therapy can effectively remove staphylococcus epidermidis and its biofilm.