宏基因组测序技术监测异基因造血干细胞移植后嗜肺军团菌感染

Application of metagenomics next-generation sequencing in monitoring Legionella pneumophila infection after allogeneic hematopoietic stem cell transplantation

目的探讨宏基因组高通量测序(mNGS)技术在少见及难培养病原菌中的应用价值。方法1例行异基因造血干细胞移植(allo-HSCT)治疗的急性淋巴细胞白血病患者于移植后出现感染症状,应用微生物培养、聚合酶链反应(PCR)及mNGS结合生物信息分析等方法检测患者血浆和脑脊液等标本中的致病原,根据检测结果调整抗感染治疗方案及评估疗效。结果患者出现感染症状后多次送检脑脊液、外周血进行微生物培养及PCR检测常见致病原,均未检测到可疑病原。移植后第23天送检脑脊液mNGS分析,发现嗜肺军团菌基因序列(序列数19655),结合临床表现考虑为致病菌。根据患者临床表现和检测结果调整抗感染药物的使用,并用mNGS方法监测嗜肺军团菌基因序列数。确定为嗜肺军团菌感染后采用阿奇霉素、替加环素、左氧氟沙星等针对性抗生素治疗。患者在5个月间共进行15次mNGS分析,脑脊液中嗜肺军团菌序列数最高2226,最低253,并最终转阴。其临床感染症状及治疗转归与mNGS监测结果相符。结论mNGS技术在少见及难培养病原菌监测中具有积极的临床应用价值,是微生物鉴定和PCR方法的有益补充。

Objective To investigate the application of metagenomic next-generation sequencing(mNGS)in detection of the rare or difficult-to-cultivate pathogens.Methods One patient with acute lymphoblastic leukemia who went through allogeneic hematopoietic stem cell transplantation(allo-HSCT)developed symptoms of infection after transplantation.Conventional microbial culture,polymerase chain reaction(PCR),and mNGS combined with biological information analysis were performed with plasma and cerebrospinal fluid samples,the anti-infective treatment was adjusted according to the test results,and the efficacy was assessed.Results No suspected pathogens were detected by microbial culture and PCR in the cerebrospinal fluid and plasma samples since the patient developed infection symptoms.However,Legionella pneumophila was analyzed by mNGS in the cerebrospinal fluid specimen on day 23 after allo-HSCT(reads count:19655),and it was considered as the principal pathogen after comprehensively evaluating the patient's clinical manifestations and the test results.Then the antimicrobial treatments were adjusted according to the patient's clinical manifestations and laboratory test results,and the number of gene sequences of Legionella pneumophila was monitored by mNGS method.Azithromycin,tigecycline,and other antibiotics effective for Legionella pneumophila were used after detecting this pathogen.A total of 15 mNGS analysis were performed during the 5-month period,and the highest number of Legionella pneumophila sequences monitored in the cerebrospinal fluid was 2226,the lowest was 253 and eventually turned negative.The clinical symptoms and treatment outcomes were consistent with the mNGS monitoring results.Conclusions The mNGS technology has significant value in detection of the rare and difficult-to-cultivate pathogens.The mNGS technology provides a valuable supplement to microbial culture and PCR methods.