Abstract:

Objective To investigate the combined determination of procalcitonin（PCT）,C-reactive protein（CRP） and white blood cell（WBC） count for the early diagnosis and treatment of hospital-acquired bacterial pneumonia （acquired pneumonia） in intensive care unit（ICU）. Methods A total of 69 patients with acquired pneumonia in ICU were enrolled,and 71 patients with non-bacterial pneumonia（pathogens including fungus,mycoplasma,parasite,rickettsia and so on）were enrolled as control group. Sputum PCT,serum PCT,serum CRP and WBC count were determined in admission,after treatment for 2 d,after treatment for 7 d and at the end of treatment,and sputum smear and culture etiology were performed simultaneously. Receiver operating characteristic（ROC） curve was used to evaluate the significance of each parameter for the diagnosis of acquired pneumonia. Results Compared with non-bacterial pneumonia group,serum PCT in acquired pneumonia group increased after treatment for 2 d,CRP increased after treatment for 7 d,WBC count reduced at the end of treatment. There was no statistical significance for the other parameters between 2 groups at different time points（P>0.05）. For acquired pneumonia group in admission and at the end of treatment,WBC count（neutrophil percentage >70% as positive） had statistical significance compared with non-bacterial pneumonia group（P<0.05）. Sputum PCT in acquired pneumonia group had no statistical significance for the 4 time points（P>0.05）,and serum PCT after treatment for 2 d was higher than those in the other time points（P<0.001）. Serum CRP in admission was the highest,with treatment,the concentration decreased,and the difference among the 4 time points were statistically significant（P<0.001）. WBC count was higher in admission than at the other time points（P<0.001）,there was no statistical significance between after treatment for 2 d and 7 d（P>0.05）,and WBC count returned to normal at the end of treatment. In non-bacterial pneumonia group,the difference of sputum and serum PCT at the 4 time points was not statistically significant（P>0.05）,and the changes of serum CRP and WBC count were consistent with those in acquired pneumonia group. The top 3 isolates in acquired pneumonia group were Pseudomonas aeruginosa,Acinetobacter baumannii and Escherichia coli. After treatment for 2 d,serum PCT in patients infected with Escherichia coli was higher than those in patients infected with Pseudomonas aeruginosa and Acinetobacter baumannii（P<0.05）,and WBC count in patients with Escherichia coli was higher than that in patients with Acinetobacter baumannii（P<0.05）. There was no statistical significance among the 3 kinds of isolates for sputum PCT and serum CRP（P>0.05）. The area under ROC curve of serum PCT was 0.921（P<0.05）,with a sensitivity of 87.5% and a specificity of 93.7%. Conclusions Serum PCT in the early diagnosis of acquired pneumonia in ICU has good sensitivity and specificity,and the combined determination of serum PCT,CRP and WBC count is of clinical significance in the diagnosis of acquired pneumonia.

Key words: Procalcitonin, C-reactive protein, White blood cell, Hospital-acquired bacterial pneumonia