呼吸道吸出物MP-DNA检测对儿童肺炎支原体肺炎诊断的临床意义

Clinical significance of MP-DNA from endotracheal aspirates in diagnosis of Mycoplasma pneumoniae pneumonia in children

目的探讨鼻咽抽吸物（NPA）和肺泡灌洗液（BALF）中肺炎支原体（MP）-DNA检测对儿童MP肺炎（MPP）诊断的意义。方法收集164例MPP患儿入院24 h内的NPA及BALF,荧光定量PCR法检测MP-DNA;同时在入院24 h内及治疗7~10 d病情好转时采集所有患儿静脉血,ELISA法检测血清特异性MPIg M。结果 164例患儿NPA的MP-DNA阳性检出率为51.8%,低于双份血清MP-Ig M阳性检出率（63.4%）（P=0.044）,两者检出一致性中等（Kappa=0.618,P〈0.01）;BALF的MP-DNA阳性检出率为71.3%,与双份血清MP-Ig M阳性检出率比较差异无统计学意义（P〉0.05）,两者检出一致性好（Kappa=0.793,P〈0.01）;NPA的MP-DNA阳性检出率低于BALF（P〈0.01）,两者检出一致性中等（Kappa=0.529,P〈0.01）。BALF中MP的中位拷贝数高于NPA（P〈0.01）。NPA和BALF MP-DNA的检出率均随病程延长有下降趋势（P〈0.05）,病程~2周及~4周患儿BALF MP-DNA检出率高于NPA（P〈0.05）。结论 BALF中MP-DNA检出敏感性高,对临床早期诊断MPP具有重要意义;而NPA MP-DNA检测可能会引起漏诊。

Objective To compare the detection rates of Mycoplasma pneumoniae （MP） from nasopharyngeal aspirates （NPA） and bronchoalveolar lavage fluid （BALF） in children with pneumonia. Methods A total of 164 hospitalized children with pneumonia were enrolled. NPA and BALF of these children were collected within 24 hours of admission, and MP-DNA was detected by lfuorescence quantitative PCR. Venous blood samples of all these children were collected within 24 hours of admission and on days 7-10 of treatment, and serum MP-IgM was detected using ELISA. Results The positive rate of MP-DNA in NAP of the 164 cases was 51.8%, which was lower than 63.4%as the detection rate of MP-IgM in serum （P=0.044）, and the two detection rates were moderately consistent with each other （Kappa=0.618, P〈0.01）. The positive rate of MP in BALF was 71.3%, which was not signiifcantly different with that of MP-IgM in serum （P〉0.05）, and the detection rates were well consistent （Kappa=0.793, P〈0.01）. The detection rate of MP in NPA was lower than that in BALF （P〈0.01）, with moderate consistency between two of them （Kappa=0.529, P〈0.01）. The median MP copy number in BALF was signiifcantly higher than that in NPA （P〈0.01）. The MP detection rates in NPA and BALF were signiifcantly different among different courses of disease （P〈0.05）. As the course of disease extended, the MP detection rates in both NPA and BALF showed a declining trend;children with MP pneumonia of 1-2 weeks＇ duration and 2-4 weeks＇ duration had a higher MP-DNA detection rate in BALF than in NPA （P〈0.05）. Conclusions MP-DNA in BALF has a high sensitivity, with a great signiifcance for early diagnosis of MP pneumonia, while NPA MP-DNA tests may lead to a missed diagnosis.