梅毒实验室诊断的研究现状与展望

Research status and perspective in laboratory diagnosis of syphilis

[背景]近年来,梅毒发病数呈逐年上升趋势,引起广泛关注,已成为全球性公共卫生问题.鉴于梅毒病程的隐匿性、复杂性和多样性,迫切需要高灵敏度的诊断方法和有效的疗效监测指标,以实现梅毒的早诊断和早治疗.[进展]本文对梅毒实验室检测方法及诊断程序的研究现状进行综述.病原学检查可以直接确诊感染,但易受取材部位及取材方法等因素影响,灵敏度较低.血清学检测是梅毒诊断的主要检测方法,但由于抗体至少在感染2周后才产生,难以筛查窗口期的患者.由于血清学诊断程序的行业标准尚未统一,各实验室对3种血清学诊断程序的选择也不尽相同.聚合酶链式反应(polymerase chain reaction,PCR)对于一期或二期梅毒患者皮损组织具有较高灵敏度和特异度,但对于较易获得的血液样本,其梅毒螺旋体(Treponema pallidum)DNA检出率低,国内至今尚无获得医疗器械注册证的梅毒PCR检测试剂,无法应用于临床检测.[展望]首先,研发梅毒螺旋体抗体和非特异性抗体联合检测试剂,避免单一试验假阴性造成的漏诊;其次,开展血液、脑脊液、尿液等标本的梅毒螺旋体抗原谱研究,缩短检测的窗口期;最后,引入质量管理体系,制定梅毒分子诊断的统一标准.

[Background]Syphilis is a sexually transmitted disease caused by Treponema pallidum,which can damage the nervous,cardiovascular,digestive and urinary systems,seriously endangering human health.In recent years,the number of syphilis cases has been increasing annually.The number of reported syphilis cases ranks third among legally reported infectious diseases,following viral hepatitis and tuberculosis,and first among sexually transmitted diseases,which has raised wide spread concern and become a global public health issue.At present,the clinical stage composition of new syphilis cases has undergone significant changes.The proportion of primary and secondary syphilis of dominant syphilis and the proportion of fetal syphilis have gradually decreased,while the incidence of recessive syphilis has increased year by year.Given that syphilis is a great imitator and its course is occult,complex and diverse,there is an urgent need for highly sensitive diagnostic methods and effective monitoring indicators to enable early diagnosis and treatment.[Progress]This article reviews the research status of laboratory detection methods and algorithms of syphilis.Pathogen examination can directly confirm infection,but it is susceptible to factors such as sampling site and sampling method,resulting in low sensitivity.Serological tests are the primary method for the diagnosis of syphilis,but because antibodies are produced at least 2 weeks after infection,it is difficult to screen patients during the window period.Due to the lack of a unified industry standard for serological diagnostic algorithms,the selection of the three serological diagnostic algorithms by various laboratories is also different.Polymerase chain reaction(PCR)has high sensitivity and specificity for lesions of patients with primary or secondary syphilis,but for easily obtained blood samples,the positive rate of T.pallidum DNA is low.To date,no syphilis PCR detection reagent has obtained a medical device registration certificate in China,preventing its clinical application.[Perspective]First,the development of a joint detection reagent for T.pallidum antibody and non-specific antibody can avoid missed diagnosis of false negative results due to the initial screening method of the three diagnostic algorithms,promptly identify the disease status of patients,and detect syphilis cases at various stages with maximum sensitivity and specificity.This approach can effectively reduce the workload and contribute to the early diagnosis of syphilis.Secondly,the detection window period of serological tests is long,generally several weeks,which often coincides with an important infectious period,facilitating the spread of disease.As the component of the pathogen itself,the antigens can appear after the pathogen has invaded the body.Research on the antigen spectrum of blood,cerebrospinal fluid,urine and other specimens is expected to shorten the detection window period.Finally,there is no internationally approved assay for syphilis PCR,and laboratories have established methods based on their own needs without rigorous performance verification and systematic evaluation.In the future,the quality control management of clinical molecular detection can serve as a reference,with evaluation and strict performance verification conducted in areas such as detection personnel,instruments and equipment,experimental reagent materials,detection methods,and laboratory environment.This will help develop unified standards for molecular diagnosis of syphilis and ultimately lead to in vitro diagnostic products of syphilis molecular detection with quality control.