Schneeberger Peter M, Hermans Mirjam H A, van Hannen Erik J, Schellekens Jeroen J A, Leenders Alexander C A P, Wever Peter C
Jeroen Bosch Hospital, Department of Medical Microbiology and Infection Control, P.O. Box 90153, 5200 ME 's-Hertogenbosch, The Netherlands.
Clin Vaccine Immunol. 2010 Feb;17(2):286-90. doi: 10.1128/CVI.00454-09. Epub 2009 Dec 23.
The world's largest Q fever outbreak is ongoing in The Netherlands with around 3,000 confirmed cases since the first half of 2007. Increased awareness has resulted in early referral of patients for diagnostics. An important drawback to serological diagnosis of acute Q fever is the lag phase in antibody response. Therefore, we evaluated the performance of a real-time PCR for detection of Coxiella burnetii DNA using serum samples from patients with acute Q fever. PCR, targeting IS1111, was retrospectively performed on acute-phase and follow-up convalescent-phase serum samples from 65 patients with acute Q fever as diagnosed by immunofluorescence assay. The results obtained by PCR were related to disease stage as defined by subsequent appearance of phase II IgM, phase II IgG, phase I IgM, and phase I IgG (IgM-II, IgG-II, IgM-I, and IgG-I, respectively) antibodies and time since onset of disease. In addition, we analyzed seronegative acute-phase serum samples from patients with inconclusive Q fever serology, because no convalescent-phase serum samples were available. PCR was scored positive in 49/50 (98%) seronegative sera, 9/10 (90%) sera with isolated IgM-II antibodies, 3/13 (23%) sera with IgM-II/IgG-II antibodies, 2/41 (5%) sera with IgM-II/IgG-II/IgM-I antibodies, 0/15 (0%) sera with IgM-II/IgG-II/IgM-I/IgG-I antibodies, and 0/1 (0%) serum sample with IgM-II/IgG-II/IgG-I antibodies. The latest time point after onset of disease in which C. burnetii DNA could be detected was at day 17. In patients with inconclusive Q fever serology, PCR was positive in 5/50 (10%) cases. We conclude that real-time PCR with serum samples is indispensable for early diagnosis of acute Q fever. C. burnetii DNA becomes undetectable in serum as the serological response develops.
荷兰正在发生全球最大规模的Q热疫情，自2007年上半年以来确诊病例约达3000例。意识的提高促使患者尽早转诊进行诊断。急性Q热血清学诊断的一个重要缺陷是抗体反应的延迟期。因此，我们使用急性Q热患者的血清样本评估了实时PCR检测伯氏考克斯体DNA的性能。以IS1111为靶点的PCR对65例经免疫荧光法诊断为急性Q热患者的急性期和恢复期血清样本进行回顾性检测。PCR结果与疾病阶段相关，疾病阶段由II期IgM、II期IgG、I期IgM和I期IgG（分别为IgM-II、IgG-II、IgM-I和IgG-I）抗体的后续出现情况以及发病后的时间确定。此外，由于没有恢复期血清样本，我们分析了Q热血清学结果不确定患者的急性期血清阴性样本。PCR在49/50（98%）血清阴性样本、9/10（90%）仅含IgM-II抗体的样本、3/13（23%）含IgM-II/IgG-II抗体的样本、2/41（5%）含IgM-II/IgG-II/IgM-I抗体的样本、0/15（0%）含IgM-II/IgG-II/IgM-I/IgG-I抗体的样本以及0/1（0%）含IgM-II/IgG-II/IgG-I抗体的样本中呈阳性。发病后能检测到伯氏考克斯体DNA的最晚时间点为第17天。在Q热血清学结果不确定的患者中，PCR在5/50（10%）的病例中呈阳性。我们得出结论，血清样本实时PCR对于急性Q热的早期诊断不可或缺。随着血清学反应的发展，血清中伯氏考克斯体DNA变得无法检测到。
