革兰染色与MALDI-TOF MS在快速鉴定儿童阳性血培养病原菌种类中的应用

Application of Gram staining and MALDI-TOF MS in the rapid identification of pathogen kinds in children's positive blood culture

目的分析革兰染色与基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)在快速鉴定儿童阳性血培养病原菌种类中的应用价值,为儿童血流感染诊断提供快速、准确的实验室依据。方法收集2019年2月—2020年10月首都医科大学附属北京儿童医院临床送检的儿童阳性血培养瓶,同时进行革兰染色镜检、MALDI-TOF MS快速鉴定和转种培养,以转种培养后的鉴定结果为标准,对革兰染色镜检和MALDI-TOF MS快速鉴定结果进行比较。结果共收集166例儿童阳性血培养样本,其中单一菌样本占97.6%(162/166),2种菌样本占2.4%(4/166)。以转种培养后的鉴定结果为标准,162例单一菌样本革兰染色镜检结果符合率为97.5%(158/162),其中革兰阳性菌符合率为97.9%(93/95),革兰阴性菌符合率为96.8%(61/63),酵母样真菌符合率为100.0%(4/4);MALDI-TOF MS快速鉴定结果符合率为85.2%(138/162),其中革兰阳性菌符合率为81.1%(77/95),革兰阴性菌符合率为92.1%(58/63),酵母样真菌符合率为75.0%(3/4)。4例2种菌样本中,革兰染色镜检结果均与转种培养后的鉴定结果一致,而MALDI-TOF MS快速鉴定只能鉴定出其中1种菌。MALDI-TOF MS快速鉴定法对革兰阴性菌的鉴定符合率明显高于革兰阳性菌,但差异无统计学意义(P>0.05)。当报阳时长(TTP)<21 h时,MALDI-TOF MS鉴定结果符合率较高(92.2%),尤其对革兰阴性菌的鉴定准确率更高(P<0.05)。结论革兰染色与MALDI-TOF MS均可在短时间内快速鉴定儿童阳性血培养中的病原菌,可为临床诊治儿童血流感染提供快速、准确的实验室依据。

Objective To study the application of Gram staining and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)in the rapid identification of pathogen kinds in children's positive blood culture,and to provide a rapid and accurate laboratory reference for children's bloodstream infection.Methods The positive aerobic blood culture bottles of children submitted for clinical examination in Beijing Children's Hospital Affiliated to Capital Medical University from February 2019 to October 2020 were collected.Gram staining microscopy,rapid identification of MALDI-TOF MS and culture were carried out.Based on the identification results after culture,the effect of Gram staining and rapid identification of MALDI-TOF MS was evaluated.Results A total of 166 positive samples of children's aerobic blood culture were collected,of which 97.6%(162/166)were single bacteria,and 2.4%(4/166)were multiple bacteria.According to the identification results after culture,the coincidence rate of Gram staining microscopy in 162 single bacterium samples was 97.5%(158/162),of which the coincidence rate of Gram-positive bacteria was 97.9%(93/95),Gram-negative bacteria was 96.8%(61/63),and the coincidence rate of yeast like fungi was 100.0%(4/4).The coincidence rate of rapid identification by MALDI-TOF MS was 85.2%(138/162),including 81.1%(77/95)of Gram-positive bacteria,92.1%(58/63)of Gram-negative bacteria and 75.0%(3/4)of yeast like fungi.Among the 42-kind bacteria samples,the results of Gram staining microscopy were consistent with those after culture,and only one of them could be identified by MALDI-TOF MS.The coincidence rate of rapid identification of Gram-negative bacteria by MALDI-TOF MS was higher than that of Gram-positive bacteria(P>0.05).When time to positivity(TTP)<21 h,the coincidence rate of MALDI-TOF MS was higher,especially for Gram-negative bacteria(P<0.05).Conclusions Gram staining and MALDI-TOF MS can rapidly identify the pathogens in children's positive blood culture in a short time,so as to provide a rapid and accurate laboratory reference for clinical diagnosis and treatment of children's bloodstream infection,and to reduce the hospitalization cost and mortality of bloodstream infection in children.