Juste R N, Hannan M, Glendenning A, Azadian B, Soni N
Magill Department of Anaesthesia, Chelsea and Westminster Hospital, London, UK.
Intensive Care Med. 2000 Sep;26(9):1373-5. doi: 10.1007/s001340000582.
To evaluate the widespread practice of using qualitative culture of venous blood taken through central venous catheters (CVCs) as a means of diagnosing catheter colonisation in situ.
A prospective clinical study.
Three hundred fifty-one CVCs were inserted into 228 critically ill patients.
Prior to CVC removal, blood was taken for qualitative culture from the CVC and a peripheral site. All catheter tips underwent semi-quantitative analysis of bacterial colony count [1].
One hundred eighteen (33.6%) CVCs were found to be colonised on removal. A positive central blood culture had a sensitivity and specificity of 50.8% and 78.9% when compared with the 'gold standard' of catheter tip culture. This gives a positive predictive value of 47.7% and a negative predictive value of 76.5%. The sensitivity and specificity of a positive peripheral blood culture were 41.5% and 77.7% with positive and negative predictive values of 48.8% and 72.9%, respectively. When only those catheters removed because of systemic sepsis (n = 139) were considered, a positive central blood culture had a sensitivity of 58.8% and a specificity of 69.3%.
Our results indicate that the use of central blood culture confers a small advantage in sensitivity compared with peripheral blood culture. This advantage was further improved by only considering the catheters removed because of systemic sepsis but at the cost of a loss of specificity. Qualitative blood culture is a poor tool for the diagnosis of in-situ CVC colonisation.
评估通过中心静脉导管（CVC）采集静脉血进行定性培养作为原位诊断导管定植方法的广泛应用情况。
一项前瞻性临床研究。
将351根CVC插入228例重症患者体内。
在拔除CVC之前，从CVC和外周部位采集血液进行定性培养。所有导管尖端均进行细菌菌落计数的半定量分析[1]。
拔除时发现118根（33.6%）CVC发生定植。与导管尖端培养的“金标准”相比，中心血培养阳性的敏感性和特异性分别为50.8%和78.9%。这使得阳性预测值为47.7%，阴性预测值为76.5%。外周血培养阳性的敏感性和特异性分别为41.5%和77.7%，阳性和阴性预测值分别为48.8%和72.9%。仅考虑因全身性脓毒症而拔除的导管（n = 139）时，中心血培养阳性的敏感性为58.8%，特异性为69.3%。
我们的结果表明，与外周血培养相比，采用中心血培养在敏感性方面具有微小优势。仅考虑因全身性脓毒症而拔除的导管时，这一优势进一步提高，但代价是特异性降低。定性血培养对于原位CVC定植的诊断是一种较差的工具。
