Department of Medical Microbiology and Infection Control, Jeroen Bosch Hospital, 's-Hertogenbosch, the Netherlands.
J Clin Microbiol. 2013 Oct;51(10):3192-8. doi: 10.1128/JCM.00993-13. Epub 2013 Jul 17.
PCR is very effective in diagnosing acute Q fever in the early stages of infection, when bacterial DNA is present in the bloodstream but antibodies have not yet developed. The objective of this study was to further analyze the diagnostic value of semiquantitative real-time PCR (qPCR) in diagnosing acute Q fever in an outbreak situation. At the Jeroen Bosch Hospital, in 2009, qPCR testing for Coxiella burnetii DNA was performed for 2,715 patients suspected of having acute Q fever (positive, n = 385; negative, n = 2,330). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the qPCR assay were calculated for patients with negative qPCR results with a follow-up sample obtained within 14 days (n = 305) and qPCR-positive patients with at least one follow-up sample (n = 369). The correctness of the qPCR result was based on immunofluorescence assay results for samples submitted for qPCR and follow-up testing. The sensitivity of the Q fever qPCR assay was 92.2%, specificity 98.9%, PPV 99.2%, and NPV 89.8%. Patients who later developed serologic profiles indicative of chronic Q fever infection had significantly higher C. burnetii DNA loads during the acute phase than did patients who did not (P < 0.001). qPCR testing is a valuable tool for the diagnosis of acute Q fever and should be used in outbreak situations when the onset of symptoms is <15 days earlier. Special attention is needed in the follow-up monitoring of patients with high C. burnetii DNA loads during the acute phase, as this might be an indicator for the development of a serologic profile indicative of chronic infection.
PCR 非常有效地诊断感染早期的急性 Q 热，此时血液中存在细菌 DNA，但尚未产生抗体。本研究的目的是进一步分析半定量实时 PCR（qPCR）在暴发情况下诊断急性 Q 热的诊断价值。在 2009 年，Jeroen Bosch 医院对 2715 例疑似急性 Q 热患者（阳性 n = 385；阴性 n = 2330）进行了柯克斯体 DNA 的 qPCR 检测。对于 qPCR 结果为阴性且在 14 天内获得随访样本的 305 例患者（n = 305）和至少有一个随访样本的 qPCR 阳性患者（n = 369），计算 qPCR 检测的敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）。qPCR 结果的正确性基于提交进行 qPCR 和随访检测的样本的免疫荧光分析结果。Q 热 qPCR 检测的敏感性为 92.2%，特异性为 98.9%，PPV 为 99.2%，NPV 为 89.8%。与未发生慢性 Q 热感染的患者相比，之后发生慢性 Q 热感染血清学特征的患者在急性阶段的 C. burnetii DNA 载量显著更高（P<0.001）。qPCR 检测是诊断急性 Q 热的有价值工具，在症状发作<15 天之前的暴发情况下应使用该检测。在急性阶段，应特别注意对高 C. burnetii DNA 载量患者的随访监测，因为这可能是发生慢性感染血清学特征的指标。
