Early diagnostic value of combined inflammatory cytokines in bloodstream infection with different organisms

Abstract

Objective To investigate the expression of procalcitonin (PCT) and C-reactive protein (CRP) , and endotoxin in bloodstream infection with different microorganisms, so as to assess the value of these inflammatory cytokines in early diagnosis of sepsis in bloodstream infections patients. Methods Data of 152 septic bloodstream infected patients with 90 male and 62 female aged from 62 to 102 years and 79.2±16.3 years in average admitted from January 2012 to December 2013 were analyzed retrospectively. According to the results of blood culture, the microorganisms could be categorized into gram-negative bacteria, gram-positive bacteria and fungus groups, and the levels of serum CRP, PCT, and endotoxin were compared among these groups of bloodstream infections patients within 24 hours after admission. Results (1) A total of 152 strains of microorganisms were surveyed including 92 gram-negative strains (61.18%) , 43 gram-positive strains (28.29%) , and 16 fungal strains (10.53%) . In the gram-negative strains, Klebsiella pneumoniae (n=29) , Acinetobacter baumannii (n=24) , Escherichia coli (n=23) , Burkholderia cepacia (n=9) and Pseudomonas aeruginosa (n=4) were the most common isolates. In the Gram-positive strains, 13 strains of Staphylococcus aureus were isolated. (2) In the gram-negative bacterial bloodstream infections group, there were 60 (64.52%) patients with endotoxin positive, and there were no endotoxin positive cases with detected gram-positive bacteria and fungal bloodstream infections. The median levels of PCT were significantly different among the three groups [gram-negative strains group: 7.760 (3.365, 28.585) ng/mL, gram-positive strains group: 0.705 (0.265, 3.225) ng/mL, fungal infection group: 1.245 (0.543, 1.998) ng/mL]. In the fungal bloodstream infection group, the mean level of CRP was higher than that in other two groups [gram-negative strains group: (126.01 ± 66.53) mg/L, gram-positive strains group: (77.58±54.21) mg/L, fungal infection group: (140.14±71.21) mg/L]. (3) The receiver operating characteristic (ROC) curve of inflammatory cytokines was made for the diagnostic value in bloodstream infections. ROC curve used to distinguish between gram-positive bacterial bloodstream infections group and fungal group showed that AUCPCT+ CRP=0.791. When PCT cut-off value was 0.92 ng/mL, and CRP cut-off value was 68.00 mg/L, the sensitivity was 50% and the specificity was 95.5%. ROC curve used to distinguish between the gram-negative bacterial bloodstream infections group and fungal group showed that AUCPCT+ CRP+ LPS=0.947. When PCT cut-off value was 2.16 ng/mL and CRP cut-off value was 94.10 mg/L, and endotoxin was positive, the sensitivity was 82.8% and the specificity was 100% . ROC curve used to distinguish between gram-negative bacterial bloodstream infections group and gram-positive bacterial group showed that AUCPCT+ CRP+ LPS=0.947. When PCT cut-off value was 2.68 ng/mL, CRP cut-off value was 106.5 mg/L, endotoxin was positive, the sensitivity was 74.2% and the specificity was 97.7% . Conclusions Gram-negative bacteria were the most common microorganisms in bloodstream infections in ICU patients. Compared with single inflammatory cytokine, the serum concentrations of PCT, CRP and endotoxin used together could provide more sensitivity and specificity for the early diagnosis of bloodstream infection with different microorganisms. Key words: Bloodstream infection; Sepsis; Gram-negative bacteria; Gram-positive bacteria; Fungal; Procalcitonin; C-reactive protein; Endotoxin