Virus Reference Department, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, United Kingdom.
J Clin Microbiol. 2011 Oct;49(10):3576-83. doi: 10.1128/JCM.00862-11. Epub 2011 Aug 24.
The laboratory diagnostic strategy used to determine the etiology of encephalitis in 203 patients is reported. An etiological diagnosis was made by first-line laboratory testing for 111 (55%) patients. Subsequent testing, based on individual case reviews, resulted in 17 (8%) further diagnoses, of which 12 (71%) were immune-mediated and 5 (29%) were due to infection. Seventy-five cases were of unknown etiology. Sixteen (8%) of 203 samples were found to be associated with either N-methyl-d-aspartate receptor or voltage-gated potassium channel complex antibodies. The most common viral causes identified were herpes simplex virus (HSV) (19%) and varicella-zoster virus (5%), while the most important bacterial cause was Mycobacterium tuberculosis (5%). The diagnostic value of testing cerebrospinal fluid (CSF) for antibody was assessed using 139 samples from 99 patients, and antibody was detected in 46 samples from 37 patients. Samples collected at 14 to 28 days were more likely to be positive than samples taken 0 to 6 days postadmission. Three PCR-negative HSV cases were diagnosed by the presence of virus-specific antibody in the central nervous system (CNS). It was not possible to make an etiological diagnosis for one-third of the cases; these were therefore considered to be due to unknown causes. Delayed sampling did not contribute to these cases. Twenty percent of the patients with infections with an unknown etiology showed evidence of localized immune activation within the CNS, but no novel viral DNA or RNA sequences were found. We conclude that a good standard of clinical investigation and thorough first-line laboratory testing allows the diagnosis of most cases of infectious encephalitis; testing for CSF antibodies allows further cases to be diagnosed. It is important that testing for immune-mediated causes also be included in a diagnostic algorithm.
报道了 203 例患者确定脑炎病因的实验室诊断策略。通过一线实验室检测对 111 例（55%）患者做出病因诊断。根据个体病例回顾进行后续检测，又确诊了 17 例（8%），其中 12 例（71%）为免疫介导性病因，5 例（29%）为感染性病因。75 例病因不明。在 203 个样本中，有 16 个（8%）与 N-甲基-D-天冬氨酸受体或电压门控钾通道复合物抗体有关。确定的最常见病毒病因是单纯疱疹病毒（HSV）（19%）和水痘-带状疱疹病毒（5%），而最重要的细菌病因是结核分枝杆菌（5%）。使用 99 例患者的 139 个样本评估了脑脊液（CSF）抗体检测的诊断价值，在 37 例患者的 46 个样本中检测到抗体。与入院后 0-6 天采集的样本相比，入院后 14-28 天采集的样本更有可能呈阳性。3 例单纯疱疹病毒（HSV）PCR 阴性病例通过中枢神经系统（CNS）中病毒特异性抗体的存在被诊断。仍有三分之一的病例无法做出病因诊断，因此被认为是病因不明。延迟采样并未导致这些病例。三分之一的病因不明感染患者的中枢神经系统内出现局部免疫激活的证据，但未发现新的病毒 DNA 或 RNA 序列。我们的结论是，通过良好的临床调查和彻底的一线实验室检测，可以诊断大多数传染性脑炎病例；CSF 抗体检测可以进一步诊断病例。在诊断算法中还应包括免疫介导性病因的检测。
