The Synovial Fluid NGAL Detection And The Development Of Diagnostic Reagent Strip For Prosthetic Joint Infection

Background: Synovial fluid biomarkers play an increasingly important role in the diagnosis of Prosthetic Joint Infection(PJI).Recent studies have indicated that(neutrophil gelatinase-associated lipocalin,NGAL)has a high sensitivity and specificity in the diagnosis of PJI.Objective: To investigate the value of NGAL in Synovial fluid in the diagnosis of PJI;to evaluate the expression of NGAL in Synovial fluid using antibiotics before admission;to evaluate the expression of acute and chronic infection on NGAL of Synovial fluid.Methods: A total of 78 patients(36 males and 42 females)who needed revision surgery in the First Affiliated Hospital of Fujian Medical University from January to February 2018,2017 were choosed.According to the American Society for Musculoskeletal Infection(MSIS)diagnostic criteria,the inclusion criteria are those requiring revision surgery and postoperative suspected infection after hip/knee joint replacement.The exclusion criteria are the presence of other body parts.Infected lesions,etc.,were divided into 50 cases in the infected group and 28 cases in the noninfected group.The concentration of NGAL in the Synovial fluid was determined by enzyme linked immunosorbent assay(ELISA).The NGAL,synovial fluid white blood cell count(SF-WBC)and multinuclear ratio were analyzed by receiver operating characteristic curve(ROC).(SF-PMN%),erythrocyte sedimentation rate(ESR),C-reactive protein(CRP)and other areas under the curve(AUC),determine its threshold,sensitivity and specificity.The effects of antibiotic group and nonantibiotics on the expression of NGAL in synovial fluid were compared by subgroup comparison;the expression of NGAL in acute infection group and chronic infection group.Results: The mean age(65.3 ± 13)years was 31(62%)with acute infection and 29(38%)with chronic infection,and 25(50%)patients were treated with antibiotics before admission.The median level of NGAL in the infected group was 3633.6 ng/ml(IQR,1332.4-10737.2),and the median level in the non-infected group was 26.8 ng/ml(IQR12.42-52.53)(p<0.0001).The threshold was At 263.5 ng/ml,the results showed a good diagnostic value with an AUC of 0.98,at this time sensitivity(92.9%)and specificity(98%).The concentration of NGAL in the synovial fluid using the antibiotic group was 5779.6 [IQR,1425.72-13071.99] ng/ml,and the concentration of NGAL in the synovial fluid of the antibiotic group was 2590.7 [IQR,932.86-8970.8] ng/ml(P=0.103),The difference was not statistically significant;the median level of acute and chronic infection group: 4406.97ng/ml(IQR1863.625-10651.6)versus 3252.61ng/ml(IQR1304.95-10721.5)(p=0.304),both The difference was not statistically significant.Conclusion: Synovial fluid NGAL is a new biomarker with high sensitivity and specificity.Diagnostic PJI has good clinical value.Joint NGAL test still has PJI patients with different course of disease and antibiotics before admission.Have a good application value.Objective: To develop a rapid and high-sensitivity quantitative detection of NGAL content in synovial fluid by immunofluorescence technique and to perform potency detection.Methods: Preliminary performance testing and clinical specimen verification were carried out on the sensitivity,precision,specificity and stability of the developed test strips.Results: Result: The standard curve linear standard curve 1a equation of the test strip: y=-0.0035x2+0.1056x+0.0031 R2=0.9985,the linear relationship is good,the standard curve 1b equation Y=3.385/[1+(x/45.91)-1.22] +0.105,R2=0.984.The detection line LOD and the limit of quantitation LOQ were 12.37 and 29.49 ng/ml,respectively,and the approximate detection range was 12.37 to 1250 ng/ml.The inter-assay and intra-assay precision of the test strips are less than 10%,and the cross-reaction rate with competitors such as human hemoglobin,human albumin,human globulin,cholesterol,triglyceride is less than 1%;test strip 1w,2w The stability of 3w and 4w was good.The average recoveries of the recovery test were 97.56%,95.73%,and 100.32%,respectively.In the clinical specimen verification,the NGAL content of the joint fluid was determined by ELISA and fluorescent immunoassay strips.The correlation equation is Y=0.7402x+314.75,r2=0.9117.Conclusion: The fluorescent immunoassay strip can be used for synovial fluid NGAL detection;the developed NGAL fluorescent immunoassay strip has the characteristics of high sensitivity,high precision,good specificity and perfect stability;it has a huge application prospects.