血清降钙素原水平判断血流感染细菌类型的价值研究

Value of Serum Procalcitonin Levels on Determining Bacterial Types in Blood Stream Infection

目的分析患者血清降钙素原（procalcitonin，PCT）水平对区分革兰阳性（G＋）菌和革兰阴性（G-）菌所致血流感染的价值。方法选取2010年10月-2012年3月期间具有感染症状的入院病人，经细菌培养，119例静脉血培养阳性的患者（G＋菌感染者53例，G-菌感染者66例）纳入实验组，39例静脉血培养阴性但其它部位标本培养阳性的患者设为对照组。通过对患者血清PCT和血浆内毒素（endotoxin，ETX）水平测定，分析G＋菌及G-菌感染血流后，患者体内PCT分布水平是否存在差异，并探讨该差异与ETX的相关性。结果经秩和检验，G-菌组与G＋菌组比较，PCT水平差异具有统计学意义（G-菌38．60±74．82ng／ml，G＋菌4．08±8．65ng／ml，n=119，u=6．202，P〈0．001），根据受试者工作曲线（re—ceiveroperatingcharacteristiccurve，ROC），当界值（cutoffvalue）设定为5．56ng／ml时，血清PCT水平区分G-与G＋菌所致血流感染的灵敏度为74．20％，特异度为86．80％；以G-及G＋分组细菌后，组内菌种比较，PCT水平差异均无统计学意义（P〉0．05）。经直线相关分析，血流感染患者血清PCT水平与对应血浆ETX浓度之间有正的直线相关关系（P〈0．01）。结论G-菌所致的血流感染患者血清PCT水平高于G-菌所致的血流感染，ETX是引起PCT水平增高的一个重要原因，血清PCT水平测定有助于区分G＋菌及G-菌所致的血流感染。

Objective To evaluate the value of serum procalcitonin （PCT） level for differentiating blood stream infection caused by Gram-positive or Gram-negative bacteria. Methods By bacterial culture, 119 patients with positive blood cultures （53 cases with Gram-positive bacteria,66 cases with Gram-negative） were included in experimental,and 39 cases of venous blood culture negative but other parts culture positive were included in control group. All patients were admitted to hospital with symptoms of infection from October 2010 to March 2012. Serum PCT and blood plasma endotoxin （ETX） level of pa- tients were measured and analyzed to find whether there was difference between Gram-positive and Gram-negative bacteria infected patients. Furthermore,to investigate the correlation between the difference and ETX. Results Serum PCT level in patients with Gram-negative bacteria infection was obviously higher than that of Gram-positive group [-（38. 60±74. 82 ）ng/ ml vs （4. 08±8. 65） ng/ml, n： 119, u= 6. 202, P〈0. 001]. According to receiver operating characteristic curve, if 5.56 ng/ ml was taken as a critical value, PCT sensitivity in the diagnosis of infection was 74. 20%,and specificity was 86.80%. When patients were divided into Gram-negative group and Gram-positive group as the infection caused by the type of bacteria,com- pared in different type bacteria of same group, there were not difference in patients＇ serum PCT level（ P〈0. 05）. There was correlation between serum PCT and blood plasma ETX by straight line correlation analysis （P〈0.01）. Conclusion Serum PCT level in patients with Gram-negative bacteria infection was obviously higher than that of Gram-positive group,and ETX was a important factor to increase serum PCT level. Serum PCT level are valuable to discriminate blood stream infection caused by Gram-negative from Gram-positive bacteria.