Real time PCR与常规血培养在血流感染未知病原体鉴定中的比较研究

Comparative Study of Real-time PCR and Blood Culture in Characterization of Unknown Pathogen in Bloodstream Infection

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。

Objective To observe the sensitivity and specificity of real-time PCR in the detection of unknown pathogen in blood-stream 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 blood-stream, but it cannot be recommended as the replacement for the blood culture test.