不同菌种血流感染患者降钙素原水平的差异

目的 探讨分别由革兰阳性菌、革兰阴性菌及真菌所致血流感染患者中血清降钙素原（PCT）动态水平的差异。方法 纳入2013年2月~2014年12月绵阳市中心医院重症医学科血培养结果阳性且为单一菌株感染的患者52例，并于感染第1、2、3、5、7、10天同步检测血清PCT。比较在革兰阳性（G⁺）菌、革兰阴性（G^-）菌及真菌所致血流感染患者之间PCT达峰时间、峰值水平、平均值、变化幅度的差异，并采用受试者工作曲线（ROC）评估PCT峰值水平对诊断及区分不同菌种所致血流感染的临床价值。结果 有效入选的血流感染患者共52例：G^-菌组29例，G⁺菌组17例及真菌组6例。3组患者PCT峰值水平、平均值和变化幅度以革兰阴性菌患者最高，真菌感染者最低，革兰阳性菌患者介于两者之间。3组PCT峰值水平中位数分别为38.52ng/ml、14.23ng/ml、3.14ng/ml，两两比较，G^-组峰值高于G⁺组及真菌组，差异有统计学意义（P<0.05）。根据ROC曲线，当界值为6.93ng/ml时，血清峰值PCT区分细菌所致血流感染的敏感度为97.8%，特异性为100%；当界值为33.44ng/ml时，血清峰值PCT区分G^-与G⁺菌所致血流感染的敏感度为65.5%，特异性为82.4%；当界值为7.60ng/ml时，血清峰值PCT区分G^-菌与真菌所致血流感染的敏感度为100%，特异性为100%；当界值为6.93ng/ml时，血清峰值PCT区分G⁺菌与真菌所致血流感染的敏感度为94.1%，特异性为100%。结论 血清PCT水平对鉴别G^-菌与G⁺菌或真菌引起的血流感染有一定的临床应用价值。

Difference of Procalcitonin Dynamic Change in Bloodstream Infections Caused by Various Pathogens

Objective To investigate the different dynamic changes of serum procalcitonin (PCT) levels in patients with blood stream infections caused by different pathogenic microorganisms. Methods Totally 52 patients with positive blood culture of a single strain were carried out from February 2013 through December 2014,and the serum PCT levels were detected simultaneously on days 1,2,3,5,7 and 10 after infection. The comparisons of PCT levels were done among Gram-negative (G^-) bacteria,Gram-positive (G⁺) bacteria and fungi in patients with bloodstream infections.The diagnostic performance of PCT peak level was determined by the receiver operating characteristic curve (ROC). Results A total of 52 patients with blood stream infection were enrolled and categorized into three different groups,namely G^- bacteria infection group (n=29),G⁺ bacteria infection group (n=17),and fungi infection group (n=6).The peak levels,average values,and daily changes were mainly found in G^- bacteria infections,followed by G⁺ bacteria infections and fungal infections.The median value of PCT level of G^- bacteria group was 38.52ng/ml,which was significantly higher than that of the other two groups with 14.23ng/ml in G⁺ bacteria group and 3.14ng/ml in fungi group,respectively (P<0.05).According to ROC,PCT at 6.93ng/ml was used to distinguish bacteria infection from fungi infection with sensitivity 97.8%and specificity 100%.PCT level at 33.44ng/ml could distinguish G^- bacteria infection from G⁺ bacteria infection with sensitivity 65.5%and specificity 82.4%.PCT at 7.60ng/ml was used to distinguish G^- bacteria infection from fungi infection with sensitivity 100%and specificity 100%.While PCT at 6.93ng/ml was used to distinguish G⁺ bacteria infection from fungi infection with sensitivity 94.1%and specificity 100%. Conclusion Serum PCT level is valid for distinguishing patients with blood stream infection caused by G^- bacteria from G⁺ bacteria or from fungi.