serum procalcitonin levels distinguish gram-negative bacterial sepsis from gram-positive bacterial and fungal sepsis

background: serum procalcitonin (pct) levels differ in patients with bacterial or fungal infections and are significantly elevated in patients with gram-negative bacteremia. we evaluated the diagnostic accuracy of different inflammatory markers to discriminate sepsis caused by different pathogens. materials and methods: we included 328 episodes of bacteremia from 292 patients with sepsis and 31 patients with suspected sepsis in this study. medical records of patients who had bacteremia caused by gram-negative bacteria (gram-negative),gram-positive bacteria (gram-positive) or fungi were reviewed, and information about pct and other inflammatory markers was recorded. the diagnostic performance of inflammatory markers was calculated via receiver operating characteristic (roc) curves. results: serum pct levels in gram-negative, gram-positive, and fungal sepsis were 7.47 (interquartile range [iqr]: 1.09–41.26) ng/ml, 0.48 (iqr: 0.15–2.16) ng/ml, and 0.60 (iqr: 0.14–2.06) ng/ml, respectively (p < 0.001). roc analysis revealed an optimal cut-off value of 2.44 ng/ml for pct in discriminating gram-negative sepsis from gram-positive sepsis,which yielded a sensitivity of 68.4% and a specificity of 77.1%. an optimal cut-off value of 3.11 ng/ml for pct in discriminating gram-negative sepsis from fungal sepsis, led to a sensitivity of 63.9% and specifi city of 93.3%. neither pct nor other inflammatory markers could be used to distinguish between gram-positive and fungal sepsis. conclusion: serum pct levels were significantly higher in patients with gram-negative sepsis than in those with gram-positive or fungal sepsis. pct is a potential sensitive biomarker for distinguishing gram-negative sepsis from gram-positive and fungal sepsis.