焦巍　彭莉

[摘要] 目的 观察real time PCR在血流感染病原体检测中的敏感性和特异性，并与常规血培养对比，探讨其临床应用价值。方法 以该院各临床科室收集的108份脓毒血症患者血液标本进行real time PCR检测，同时进行常规血培养，比较两种方法的特异性和敏感性。结果 108份标本当中，两种方法检测出12种病原微生物。Real time PCR共检测出阳性标本25份，阴性标本83份。其中与血培养共同阳性标本9份，共同阴性标本78份。两方法的一致性为80.6%。Real time PCR的阴性预测值是0.94，敏感性64%，特异性83%。16例标本real time PCR阳性而血培养阴性，5例标本血培养阳性而real time PCR阴性。同时，有2病标超出real time PCR的检测范围，而血培养阳性。此外，real time PCR无法检测光滑念珠菌。结论 real time PCR虽然能快速检测血液感染中病原微生物，但依然不能完全替代血培养。

[关键词] 实时定量PCR；血流感染；血培养

[中图分类号] R4 [文献标识码] A [文章编号] 1674-0742（2014）05（c）-0031-02

[Abstract] Objective To observe the sensitivity and specificity of real-time PCR in the detection of unknown pathogen in bloodstream infection， and compare that with conventional blood culture， and thus to investigate its clinic application value in pathogen detection. Methods A total of 108 blood samples of patients with sepsis from the clinic departments in our hospital were collected for real-time PCR detection and conventional blood culture. And the sensitivity and specificity of these two methods were compared. Results Of the 108 samples， 12 kinds of pathogens were detected. 25 positive and 83 negative samples were detected by real-time PCR. 9 samples were positive， and 78 samples were negative in both real-time PCR and blood culture assays. The agreement rate of blood culture system and real-time PCR was 80.6%. The negative predictive value of real-time PCR was 0.94， sensitivity was 64%， and specificity 83%. In 16 samples where a positive real-time PCR and a negative blood culture system result were obtained. In 5 samples， the blood culture assay was positive whereas the real-time PCR yielded negative results. In 2 of these cases， the pathogens involved were not included in the real-time PCR detection list but positive in blood culture assay. In addition， real-time PCR failed to detect Candida glabrata. Conclusion Real-time PCR is a rapid and valuable tool for rapid diagnosis of pathogens in the bloodstream， but it cannot be recommended as the replacement for the blood culture test.

[Key words] Real-time PCR； Bloodstream infection； Blood culture

对于脓毒血症患者而言，准确快速快速血流病原体，是指导抗生素治疗最有效的措施[1]。尽管经验性使用抗生素可及时挽救患者生命，但由于耐药菌逐年增多，因此对于抗生素疗效甚微的患者，有必要根据病原体的类型调整治疗手段[2]。传统诊断血流感染的方式是血培养，虽然目前全自动的仪器已经广泛应用与临床，但最终的培养结果往往是需要等待12～48 h。对于生长缓慢且营养需求复杂的病原体（如酵母菌）可能需要更长的时间。更为重要的是，若患者先前使用过抗生素，血培养的阳性率一般更低[3]。随着分子生物学技术的发展和应用，直接从血液标本中对细菌或真菌的核酸进行扩增是鉴定病原体感染的有效手段[4-5]。……