降钙素原、C反应蛋白在不同细菌血流感染中的应用价值

Application Value of Procalcitonin and C-reactive Protein in Different Bacterial Bloodstream Infections

目的 探讨血清降钙素原(procalcitonin,PCT)和C反应蛋白(C-reactive protein,CRP)在鉴别革兰阳性菌和革兰阴性菌所致的血流感染中(bloodstream infection,BSI)的应用价值,为临床医生早期诊断和治疗提供依据。方法 选取2019年1月—2020年12月在昆明医科大学附属延安医院同时进行血培养、PCT和CRP检测的住院患者为研究对象,共334例,收集患者血培养、PCT和CRP的测定结果,比较血培养阳性组和阴性组PCT和CRP检测水平之间的差异;进一步比较血培养阳性病例中革兰阳性菌、革兰阴性菌血流感染患者之间的PCT及CRP水平差异,并分别对革兰阳性菌组和革兰阴性菌组做受试者工作特征(receiver operating characteristic,ROC)曲线,确定PCT及CRP最佳诊断值以及对应的敏感度、特异度。结果 共收集到同时测定血培养、PCT和CRP的患者334例。血培养阳性患者为153例,PCT水平为1.26 (0.27,22.62)μg/L,CRP水平为100.68(25.00,178.69)mg/L;血培养阴性为181例,PCT水平为0.27(0.11,1.15)μg/L,CRP水平为33.98(2.15,128.91)mg/L。采用Mann-Whitney U检验比较血培养阳性组和血培养阴性组PCT,差异有统计学意义(U=8 843.0,P<0.001);两组间CRP比较差异有统计学意义(U=9 740.5,P<0.001)。血培养阳性组中革兰阳性菌感染患者60例,PCT和CRP的水平分别为0.33(0.13,1.21)μg/L、52.37(10.43,129.83)mg/L;革兰阴性菌感染患者93例,PCT和CRP的水平分别为8.57(0.61,43.23)μg/L、128.21(43.38,194.09)mg/L。Mann-Whitney U检验比较革兰阳性菌组与革兰阴性菌组间PCT水平,差异有统计学意义(U=1 291,P<0.001);CRP水平比较差异有统计学意义(U=1 983.5,P=0.003)。分别对革兰阳性菌组和革兰阴性菌组做ROC曲线,PCT和CRP在革兰阳性菌组的曲线下面积分别为0.527(95%CI 0.444~0.609)、0.583(95%CI 0.508~0.659);在革兰阴性菌组的曲线下面积分别为0.790 (95%CI0.721~0.839)、0.690(95%CI 0.626~0.754),PCT诊断革兰阴性菌的最佳诊断界值为1.96μg/L,此时的敏感度为64.5%,异度为81.8%;CRP用来鉴别革兰阴性菌感染的最佳诊断界值是91.7 mg/L,其敏感度为65.6%,特异度为69.6%。结论 PCT和CRP对鉴别革兰阳性菌与革兰阴性菌血流感染有一定的临床应用价值。

Objective To investigate the role of serum procalcitonin(PCT) and C-reactive protein(CRP) in differentiating bloodstream infection(BSI) caused by gram-positive and gram-negative bacteria) application value to provide a basis for early diagnosis and treatment for clinicians.Methods A total of 334 inpatients who underwent simultaneous blood culture,PCT and CRP detection in Yan’an Hospital Affiliated to Kunming Medical University from January 2019 to December 2020 were selected as the research subjects.The blood culture,PCT and CRP measurement results were collected,to compare the differences in the detection levels of PCT and CRP between the positive and negative blood culture groups.The differences of PCT and CRP levels between Gram-positive bacteria and Gram-negative bacteria bloodstream infection patients in blood culture-positive cases were further compared and analyzed.Receiver operating characteristic(ROC) curves were made for the Gram-positive bacteria group and the Gram-negative bacteria group,respectively,to determine the best diagnostic values of PCT and CRP,as well as the corresponding sensitivity and specificity.Results A total of 334 cases with simultaneous determination of blood culture,PCT and CRP were collected.There were 153 positive blood culture cases,the PCT level was 1.26(0.27,22.62) μg/L,and the CRP level was 100.68(25.00,178.69) mg/L;blood culture was negative in 181 cases,PCT level was 0.27(0.11,1.15) μg/L,and CRP level was 33.98(2.15,128.91) mg/L.Mann-Whitney U test was used to compare PCT between positive blood culture group and negative blood culture group,and the difference was statistically significant(U=8 843.0,P<0.001);the difference of CRP comparison between the two groups was statistically significant(U=9740.5,P<0.001).In the blood culture positive group,there were 60 cases of gram-positive bacteria infection,and the levels of PCT and CRP were 0.33(0.13,1.21) μg/L and 52.37(10.43,129.83) mg/L,respectively;there were 93 cases of gram-negative bacterial infection,and the levels of PCT and CRP were 8.57(0.61,43.23) μg/L and 128.21(43.38,194.09) mg/L,respectively;Mann-Whitney U test compared PCT levels between Gram-positive bacteria group and Gram-negative bacteria group,and the difference was statistically significant(U=1 291,P<0.001);the difference of comparison of CRP levels was statistically significant(U=1 983.5,P=0.003).The ROC curves of the gram-positive bacteria group and the gram-negative bacteria group were respectively made,and the areas under the curve of PCT and CRP in the gram-positive bacteria group were 0.527(95%CI 0.444-0.609) and 0.583(95%CI 0.508-0.659),respectively;the areas under the curve of the Gram-negative bacteria group were 0.790(95%CI 0.721-0.839) and0.690(95%CI 0.626-0.754),respectively;the optimal diagnostic cut-off value of PCT for diagnosing Gram-negative bacteria was 1.96 μg/L,the sensitivity at this time was 64.5%,and the isodegree was 81.8%;the best diagnostic cut-off value of CRP used to identify gram-negative bacterial infection was 91.7 mg/L,with a sensitivity of 65.6%and a specificity of 69.6%.Conclusion PCT and CRP have certain clinical application value in differentiating gram-positive bacteria and gram-negative bacteria bloodstream infection.