儿童下呼吸道感染两种方法检测肺炎支原体IgM结果差异性分析

Analysis of two different methods for detecting Mycoplasma pneumoniae IgM in children with lower respiratory tract infection

目的 :探讨间接免疫荧光法(indirect immunofluorescence assay,IFA)和被动颗粒凝集法(passive particle agglutination,PPA)在儿童下呼吸道肺炎支原体(Mycoplasma pneumoniae, MP)感染诊断中的应用价值。方法 :回顾性分析388例下呼吸道感染患儿双份血清PPA和IFA检测MP-IgM的结果,分析不同病程中2种检测方法的阳性率差异。结果:388例血清标本中总MP-IgM检出率为32.5%(126/388)。2种不同方法的检测结果受发热天数的影响有所差异,发热0~3 d时PPA与IFA 2种方法间的MP-IgM阳性检出率差异无统计学意义(P>0.05),而随着发热天数增加,两者出现差异,发热天数4 d以上,PPA法检测MP-IgM阳性率为25.14%(119/388),高于IFA法的检出率(18.0%,70/388),2次检出结果间比较差异有统计学意义(P<0.05),缺乏一致性(Kappa=0.126)。结论:对于儿童下呼吸道感染诊断,在无发热及发热1~3 d的病例中PPA与IFA测得的MP-IgM结果间差异无统计学意义;在发热4 d以上病例中,2种检测结果间有差异,此时进行联合检测有利于MP-IgM的检出。

Objective: To investigate the value of indirect immunofluorescence(IFA) and passive agglutination(PPA)for the diagnosis of Mycoplasma pneumonia(MP) infection in children with lower respiratory tract infection. Methods:The detection of serum MP-IgM via PPA and IFA in 388 children with lower respiratory tract infection was analyzed, including the difference in positive rates of the two methods in different time points during the course of disease. Results:The overall positive rate of MP-IgM was 32.5%(126/388). The detecting results were influenced by days of fever, and there was no significant difference between the two methods when the fever was 0-3 days(P>0.05). There was a difference in positive detection rates between the two methods with the increase in days of fever. For fever more than 4 days, the posi-tive detection rate of PPA(25.14%, 119/388) was higher than that of IFA(18.0%; 70/388)(P<0.05). A lack of consistency was existed between the two methods(Kappa=0.126). The specificity of IFA method(97%) was higher than that of PPA(82%), and the sensitivity of PPA method(90%) was higher than that of IFA(53%). Conclusions: In children with mycoplasma pneumonia infection of lower respiratory tract, there is no significant difference in positive detection rate between the two methods for cases with no fever or with fever 1-3 d. However, for cases with fever over 4 days, detection of MP-IgM using combined PPA and IFA is conducive to the positive detection of MP-IgM.