Parikh Harshal R, De Anuradha S, Baveja Sujata M
Department of Microbiology, L. T. M. Medical College, Sion, Mumbai, Maharashtra, India.
J Lab Physicians. 2012 Jul;4(2):89-93. doi: 10.4103/0974-2727.105588.
Physicians and microbiologists have long recognized that the presence of living microorganisms in the blood of a patient carries with it considerable morbidity and mortality. Hence, blood cultures have become critically important and frequently performed test in clinical microbiology laboratories for diagnosis of sepsis.
To compare the conventional blood culture method with the lysis centrifugation method in cases of sepsis.
Two hundred nonduplicate blood cultures from cases of sepsis were analyzed using two blood culture methods concurrently for recovery of bacteria from patients diagnosed clinically with sepsis - the conventional blood culture method using trypticase soy broth and the lysis centrifugation method using saponin by centrifuging at 3000 g for 30 minutes.
Overall bacteria recovered from 200 blood cultures were 17.5%. The conventional blood culture method had a higher yield of organisms, especially Gram positive cocci. The lysis centrifugation method was comparable with the former method with respect to Gram negative bacilli. The sensitivity of lysis centrifugation method in comparison to conventional blood culture method was 49.75% in this study, specificity was 98.21% and diagnostic accuracy was 89.5%. In almost every instance, the time required for detection of the growth was earlier by lysis centrifugation method, which was statistically significant. Contamination by lysis centrifugation was minimal, while that by conventional method was high. Time to growth by the lysis centrifugation method was highly significant (P value 0.000) as compared to time to growth by the conventional blood culture method.
For the diagnosis of sepsis, combination of the lysis centrifugation method and the conventional blood culture method with trypticase soy broth or biphasic media is advocable, in order to achieve faster recovery and a better yield of microorganisms.
医生和微生物学家早就认识到,患者血液中存在活的微生物会带来相当高的发病率和死亡率。因此,血培养已成为临床微生物实验室中用于诊断败血症的极其重要且经常进行的检测。
比较败血症病例中传统血培养方法和裂解离心法。
对200例败血症病例的非重复血培养样本同时使用两种血培养方法进行分析,以从临床诊断为败血症的患者中分离细菌——一种是使用胰蛋白酶大豆肉汤的传统血培养方法,另一种是使用皂苷并以3000g离心30分钟的裂解离心法。
从200份血培养样本中总体分离出细菌的比例为17.5%。传统血培养方法的微生物回收率更高,尤其是革兰氏阳性球菌。在革兰氏阴性杆菌方面,裂解离心法与前一种方法相当。在本研究中,与传统血培养方法相比,裂解离心法的灵敏度为49.75%,特异性为98.21%,诊断准确率为89.5%。几乎在每种情况下,裂解离心法检测到生长所需的时间更早,这具有统计学意义。裂解离心法的污染极少,而传统方法的污染较高。与传统血培养方法的生长时间相比,裂解离心法的生长时间差异具有高度统计学意义(P值0.000)。
为诊断败血症,提倡将裂解离心法与使用胰蛋白酶大豆肉汤或双相培养基的传统血培养方法相结合,以实现更快的微生物回收和更高的回收率。