宏基因组二代测序技术检测病原菌在诊断假体周围感染中的作用

Detection of periprosthetic joint infection pathogens by metagenomic next-generation sequencin

目的探讨宏基因组二代测序技术(metagenomic next-generation sequencing,mNGS)对关节假体周围感染患者关节液和超声裂解液的病原菌检出能力及诊断价值。方法收集2018年5至11月接受人工关节翻修术的患者35例,男22例,女13例;年龄(63.1±14.7)岁(范围27~90岁)。髋关节翻修11例,膝关节翻修24例;翻修原因为关节假体周围感染20例,无菌性松动15例。采集术前或术中关节液及取出假体的超声裂解液,行mNGS检测;术中采集关节液、假体周围组织和超声裂解液,行微生物培养。采集另3例初次人工关节置换患者的关节液行超声裂解,作为阴性对照。比较关节液和超声裂解液mNGS检测、微生物培养结果及对关节假体周围感染诊断的敏感性和特异性。结果13例培养阳性的关节假体周围感染病例中,12例关节液mNGS阳性,其中7例与培养结果在种水平完全一致、1例在属水平一致;13例超声裂解液mNGS阳性,其中9例与培养结果在种水平完全一致、1例在属水平一致。7例培养阴性的PJI病例中,6例关节液与超声裂解液mNGS均阳性,且在种水平一致;另1例仅超声裂解液mNGS阳性。15例无菌性松动病例中,培养及关节液mNGS均阴性,仅1例超声裂解液mNGS阳性。3例阴性对照的关节液、超声裂解液培养及mNGS均为阴性。全部病例中,mNGS在超声裂解液中共检出24种病原菌,关节液中检出22种。超声裂解液mNGS产生的原始reads数量、人源核酸比例与关节液mNGS的差异无统计学意义,但其微生物reads数量、种水平严格比对病原reads数量明显高于关节液mNGS。关节液mNGS和超声裂解液mNGS对PJI的诊断敏感度分别为90.0%和100.0%,两者之间无差异,均高于关节液培养及组织培养(分别为40.0%、60.0%);关节液mNGS的敏感度与超声裂解液培养(65.0%)无明显差异;超声裂解液mNGS的敏感度高于超声裂解液培养。各种微生物检测方法的特异度无明显差异。结论mNGS技术检测关节液或超声裂液均可准确诊断关节假体周围感染和检出样本中的病原菌;mNGS可从超声裂解液中检出更多的病原菌及更高的reads数量。mNGS检测关节液可满足大部分假体周围感染病例的临床和病原诊断需要,部分疑难病例可采用mNGS检测超声裂解液。

Objective To investigate and compare the capability of metagenomic next-generation sequencing (mNGS) in detecting pathogens and diagnosing of periprosthetic joint infection (PJI) from synovial fluid and sonicate fluid of patients who underwent revision arthroplasty. Methods Thirty-five consecutive patients who underwent revision arthroplasty from May 2018 to November 2018 were included prospectively. There were 22 males and 13 females, 11 hip revisions and 24 knee revisions. All the patients were divided into the PJI group and aseptic loosening (AL) group. Synovial fluid and sonicate fluid of the explanted prostheses were obtained for microbiological culture and mNGS tests. Periprosthetic tissues were only collected for culture. Synovial fluid of three patients undergoing primary arthroplasty been treated by sonication as the negative control group concurrently. Comparisons of microbiological results and diagnostic value from mNGS and culture tests were performed. Results In the 13 culture-positive PJI patients, mNGS results of synovial fluid were positive in 12 cases, while culture and mNGS results were completely consistent at species level in 7 cases, consistent at the genus level in 1 case. mNGS results of sonicate fluid were positive in 13 cases, while culture and mNGS results were completely consistent at species level in 9 cases, consistent at the genus level in 1 case. In 7 culture-negative PJI patients, 6 cases had consistent mNGS results at species level both from synovial fluid and sonicate fluid, however, one case had positive mNGS result only from sonicate fluid. All culture results and mNGS results of synovial fluid were negative in all 15 AL patients, however, mNGS results of sonicate fluid was positive in 1 AL case. Cultures and mNGS results were negative in all three pairs of negative-control samples. In all 70 samples, mNGS detected 24 pathogens in sonicate fluids and 22 pathogens in synovial fluids. There was no significant difference in number of raw reads and human reads ratio between mNGS of sonicate fluid and synovial fluid. mNGS of sonicate fluid generated significantly higher number of microbial reads and of stringently mapped reads of pathogen in species-level than that of synovial fluids. There was no significant difference in diagnostic sensitivity of PJI between mNGS of sonicate fluids and synovial fluids (90.0% vs 100.0%). Both of them were significantly higher than that of culture of synovial fluid, periprosthetic tissues. Diagnostic sensitivity of sonicate fluid mNGS was not significantly higher than that in culture of sonicate fluid (65%). The specificities were similar among various microbiological testing methods. Conclusion mNGS of either synovial fluid or sonicate fluid from patients who underwent revision arthroplasty can be used to detect the presence of pathogens effectively and diagnose PJI accurately. mNGS can identify more pathogens and generate a higher number of pathogenic reads from sonicate fluids than synovial fluid. mNGS of synovial fluids has met the clinical diagnostic demands for most PJI patients. mNGS of sonicate fluid could be applied in some cases.