感染性疾病的实验诊断2010.12

Identifying Bacteria that Cause Disease



Principles of Diagnostic Medical Microbiology (4) DNA-DNA or DNA-RNA hybridization to detect

pathogen-specific genes in patients' specimens. (5) Detection and amplification of organism nucleic acid in patients' specimens. (6) Demonstration of meaningful antibody or cellmediated immune responses to an infectious agent.
Identifying Bacteria that Cause Disease


Principles of Diagnostic Medical Microbiology
Physicians who deal with infectious processes must know when and how to take specimens, what laboratory examinations to request, and how to interpret the results. Clinical information is much more important for diagnostic microbiology than it is for clinical chemistry or hematology. The clinician must make a tentative diagnosis rather than wait until laboratory results are available.
了解当今感染病特点、感染类型
Specimen Collection
1.
Successful laboratory diagnosis of a microbial infection depends on many factors beginning with a well-collected sample.
Site and Timing
1.
Collect the sample from the correct anatomic site . eg. a superficial sample of a
lesion is not useful in identifying the cause of a deep wound infection.
2.
Proper specimen selection, collection, and transport are all essential to ensure that a specimen is representative of the disease process and minimally contaminated with microorganisms present in adjacent tissues.
2.
The timing of sample collection is also important. eg, when submitting a
specimen for bacterial culture, samples should be collected before the administration of antibiotics
（一）细菌感染性疾病 常用实验室检测项目的组合
3.根据标本来源，通常构成不同组合的检验方法：
（1）无菌性标本（血液、脑脊液、体腔渗出液），采用 显微镜检查和直接药敏试验可作为病原学诊断和提供临床 治疗用药指导； （2）脓血便，采用革兰染色无诊断意义，需用标记抗体 染色镜检获初步报告，再需经选择培养基分离培养，挑取 可疑菌落作玻片血清凝集，阳性者可初步鉴定，再用配套 生化反应可作出最后报告； （3）尿液标本，显微镜检查可初步估计细菌菌量，作 出初步诊断，再经分离培养鉴定后和菌落定量计数可作出 病原学诊断；④痰标本，采用显微镜检查，判定是否为合 格标本，若为合格标本作分区划线接种，检出致病性菌落， 再进行鉴定和药敏。
Identifying Bacteria that Cause Disease



Principles of Diagnostic Medical Microbiology Introduction Diagnostic medical microbiology is concerned with the etiologic diagnosis of infection. Laboratory procedures used in the diagnosis of infectious disease in humans include the following:
Identifying Bacteria that Cause Disease


Principles of Diagnostic Medical Microbiology (1) Morphologic identification of the agent in stains

of specimens or sections of tissues (light and electron microscopy). (2) Culture isolation and identification of the agent. (3) Detection of antigen from the agent by immunologic assay (latex agglutination, EIA, etc) or by fluorescein-labeled (or peroxidase-labeled) antibody stains.
细菌感染性疾病 常用实验室检测项目的组合
4.结果报告可由实验室人员可分别出具： 先后和程度不同报告各检测项目（显微镜检查、 分离培养、血清学试验、生化鉴定和PCR等核酸 检测）结果，为临床提供信息。 5.为保证细菌感染正确诊断，必须遵循下述细菌感 染诊断原则：①要求医师和检验师的密切配合， 不应停留在化验单往来；②重视检验标本的采集 和送检；③重视检验过程的阶段性和连续性；④ 检验程序需有针对性和综合性。
Transport of Specimens
1. 2.
3.
Rapid, optimally in less than 2 hours. For delays in transport, most specimens should be refrigerated. Exceptions: blood, cerebrospinal fluid (CSF), and specimens to be examined for anaerobes, fastidious organisms such as Neisseria gonorrboeae and Bordetella pertussis, and Trichomonas vaginalis, all of which should be maintained at room temperature.
Collection Techniques
1. 2. 3.
Sufficient volume Sterile technique and equipment. After collection, the specimen must be placed in an appropriately labeled leak-proof container.
难点/重点解读
（一）细菌感染性疾病常用实验室检测项目的组合
（二）病毒感染性疾病常用实验室检测项目的组合
（三）真菌感染性疾病常用实验室检测项目的组合
（四）寄生虫感染性疾病常用实验室检测项目的组合
细菌感染性疾病 常用实验室检测项目的组合
1. 感染病的实验诊断方法虽按基本原则进
行，但细感染性疾病具下述特点：
（1）诊断疾病的病原学，一般情况下只需鉴定到细菌的 种，必要时再进一步鉴定； （2）提供治疗方案，可以进行临床标本的直接药物敏感 试验，还可根据分离出病原菌的种类直接提供选择 抗生素的范围和种类； （3) 研究流行病学，必须对病原菌做进一步鉴定，往往 鉴定到型（血清型或基因型）的水平； (4) 要了解这类细菌的致病性，必须进行细致鉴定，包 括毒素、侵袭性酶类的检测。
感染性疾病的实验诊断
主要学习内容及要求
掌握 感染性疾病的常用实验室检测项目及其临床意义和评价
不同病原体感染性疾病实验室检测与不同系统病原体感 染性疾病实验室检测特点 熟悉 引起血流感染、中枢神经系统感染、呼吸系统感染、 消化系统感染、 泌尿系统感染、皮肤及软组织感染 和先天及新生儿感染常见病原体与常见疾病及病原学检 查、常见医院感染病原体及特点、医院感染的微生 物学检测及医院感染暴发流行的识别和处理
在检查项目中，尤其以细菌分离培养鉴定为 主。在无菌标本中检查到细菌，则此细菌为感染 的病原；存在正常菌群的标本中检查到细菌，应 区分是正常寄居的菌群或是致病的细菌，常需要 作细菌定量计数，根据细菌数判断是否为感染的 病原菌。
细菌感染性疾病 常用实验室检测项目的组合
2. 根据目的不同，检测项目的选择是：
Identifying Bacteria that Cause Disease

Principles of Diagnostic Medical Microbiology Communicationatory