Kelly M, Wciorka L R, McConico S, Peterson L R
Department of Pathology, Northwestern University Medical School, Chicago, Illinois, USA.
Am J Clin Pathol. 1996 Feb;105(2):210-5. doi: 10.1093/ajcp/105.2.210.
Microbial quantification of potentially infected intravenous catheters is used to determine whether the removed device may be the source of sepsis. In this study, the authors defined a clinically significant colony count using the sonication technique to implicate the catheter as the source of sepsis. The utility of a cytocentrifuge-prepared Gram's stain of sonication broth as a rapid test for the accurate diagnosis of catheter-related bacteremia and fungemia was also evaluated. Initially, 230 consecutive vascular catheter cultures were performed. In 14 patients, the blood culture was found to grow in the same organism as the catheter culture. The eight blood-culture positive patients with probable catheter-related sepsis had four catheters with 10(4)-10(5), and four with more than 10(5) CFU derived from the catheter sonication broth. Six bacteremias not catheter related showed three catheters with < 10(3), two with 10(3)-10(4), and one with > 10(5) CFU. One catheter-related bacteremia had a negative culture. A subsequent validation study on 175 catheter specimens using 1,000 CFU as a cut-off between a positive and negative test fully separated eight patients with catheter-related bacteremia from six patients with infection at a distant site. Cytospin Gram stain, studied in the initial evaluation, was positive in 17 catheters with < 10(3) CFU, 4 at 10(3)-10(4), 4 at 10(4)-10(5) and 9 with > 10(5) CFU in the sonication broth. No correlation was found between this test and catheter-related sepsis. From these results, the authors concluded that those catheters with counts below 10(3) CFU in the catheter sonication broth do not appear to have an association with catheter-related sepsis, and that a Cytospin Gram stain done with the sonication technique does not correlate with the presence of catheter sepsis.
对潜在感染的静脉导管进行微生物定量分析，以确定拔除的导管是否可能是败血症的源头。在本研究中，作者使用超声处理技术定义了具有临床意义的菌落计数，以表明导管是败血症的源头。还评估了细胞离心机制备的超声处理肉汤革兰氏染色作为准确诊断导管相关菌血症和真菌血症的快速检测方法的效用。最初，进行了230次连续的血管导管培养。在14名患者中，发现血培养生长的微生物与导管培养相同。8名可能患有导管相关败血症的血培养阳性患者，有4根导管的超声处理肉汤中菌落形成单位（CFU）为10⁴ - 10⁵，4根导管的CFU超过10⁵。6例与导管无关的菌血症患者，其3根导管的CFU < 10³，2根导管的CFU为10³ - 10⁴，1根导管的CFU > 10⁵。1例导管相关菌血症患者培养结果为阴性。随后对175份导管标本进行的验证研究中，以1000 CFU作为阳性和阴性检测的临界值，成功区分了8例导管相关菌血症患者和6例远处感染患者。在初始评估中研究的细胞离心涂片革兰氏染色，在超声处理肉汤中CFU < 10³的17根导管、CFU为10³ - 10⁴的4根导管、CFU为10⁴ - 10⁵的4根导管以及CFU > 10⁵的9根导管中呈阳性。未发现该检测与导管相关败血症之间存在相关性。基于这些结果，作者得出结论，导管超声处理肉汤中菌落计数低于10³ CFU的导管似乎与导管相关败血症无关，并且用超声处理技术进行的细胞离心涂片革兰氏染色与导管败血症的存在无关。
