| Objective In this study,we evaluated whether the performance index of Chemiluminescent Immunoassay(CLIA)in the detection of Mycoplasma pneumoniae(M pneumoniae)typed antibodies met the specified requirements,provided quick and simple detection methods through methodological comparative study,and deeply explored the application value of CLIA in the diagnosis of M pneumoniae pneumonia(MPP)in children.Methods(1)Performance verification:According to the evaluation protocol,we evaluated the minimum detectability,repeatability,inter-batch precision,linear range,and clinical coincidence rate of M.pneumoniae typed antibodies[(Anti-M.pneumoniae immunoglobulin M antibody(MP-IgM)and Anti-M.pneumoniae immunoglobulin G antibody(MP-IgG)]detected by CLIA.(2)Methodological comparative study:M.pneumoniae antibodies in 280 patients with suspected M.pneumoniae pneumonia were detected by CLIA,Enzyme linked immunosorbent assay(ELISA)and Passive agglutination(PA)method,comparing the methodology and explore its advantages and disadvantages.(3)Clinical application research:CLIA was used to detect M.pneumoniae typing antibodies in 387 children with community-acquired pneumonia,which was divided into MPP group and NMPP group.Comprehensive analysis was conducted through two groups of clinical data,laboratory results,ROC curve and follow-up status.Results(1)The limit of blank,limit of detection and limit of quantitation of MP-IgG detected by CLIA were 1.9 AU/mL,4.5 AU/mL and 5.1 AU/mL,respectively.In a linear range of 2～300 AU/mL,the MP-IgG linear fit was good,which R2≥0.99 and 0.85<b<1.15.Repeatability:Coefficient of variation(CV)of high concentrations of MP-IgG and low concentrations of MP-IgG was 2.98%and 2.45%,respectively,and CV of high concentrations of MP-IgM and low concentrations of MP-IgM was 2.55%and 2.86%,respectively.Daytime precision:CV of high concentrations of MP-IgG and low concentrations of MP-IgG was 6.44%and 6.83%,respectively,and CV of high concentrations of MP-IgM and low concentrations of MP-IgM was 4.82%and 5.46%,respectively.Clinical coincidence rate:the positive coincidence rate of MP-IgG and MP-IgM was 80%and 95%respectively,and the total clinical coincidence rate was 90%and 97.5%respectively,which showed good agreement with clinical diagnosis.(2)The Kappa values of MP-IgG and MP-IgM detected by CLIA and ELISA were 0.853(P<0.001)and 0.874(P<0.001),and the agreement percentage was 93.6%and 94.3%respectively,indicating good agreement between CLIA and ELISA.The Kappa value of CLIA and PA method was 0.541(P=0.063,there was no statistically significant difference),and the agreement percentage was 79.6%.In the M.pneumoniae antibodies positive group detected by PA method,the negative proportion of MP-IgG and MP-IgM measured by CLIA and ELISA was up to 40%,suggesting that the results measured by PA method may contain other types of antibodies except IgM,IgG.(3)The clinical manifestations of M.pneumoniae infection and the conventional detection indicators have no diagnostic specificity between the two groups,While the rapid quantitative detection of MP-IgM and MP-IgG is important for the early diagnosis of M.pneumoniae infection.The levels of MP-IgM and MP-IgG were higher in the MPP group than in the NMPP group(Z=-10.507 and-10.651 respectively,P<0.001).Results of the ROC curve:MP-IgM>1S/CO and MP-IgG>14.15AU/mL were significant predictors of M.pneumoniae infection,and the area under the curve(AUC)was 0.810 and 0.815,respectively;the standard error was 0.021 and 0.022,respectively;95%Confidence interval was 0.768-0.852,0.773-0.858,respectively;the sensitivity was 74.3%and 62.1%,respectively;the specificity was 72.9%and 87.0%,respectively.The combination of MP-IgM and MP-IgG showed higher diagnostic sensitivity and AUC,compared with MP-IgM or MP-IgG detected alone.Of the 120 children with M.pneumoniae pneumonia followed,79(65.8%)were treated with azithromycin,and 68(86.1%)recovered within 2 weeks of medication.Conclusion All the performance indexes of MP-IgM and MP-IgG tested by CLIA are within the scope of the manufacturer’s statement and meet the specified performance indexes.CLIA based on automatic chemiluminescence immunoanalyzer,which can realize rapid quantitative detection,has the advantages of high sensitivity,strong specificity,wide detection range,stable reagent and methodology.Therefore,CLIA is better than ELISA and PA method,and it is the development trend of immunoassay technology to gradually replace the time-consuming manual method with CLIA.Quantitative detection of M.pneumoniae typing antibody by CLIA has good applications in assisting the diagnosis of MPP in children,and combined detection is helpful to improve the efficiency of clinical diagnosis. |
