[Procalcitonin as a predictor of bacteremia in postoperative cardiosurgery patients]

To define diagnostics ability of procalcitonin (PCT) test for prediction of bacteremia of different etiology in cardio-surgical patients.

10158 pairs of blood examples from cardio-surgical patients in early postoperative period were studied from 2007 to 2012. Results of PCT test were compared with blood cultures. The data is presented as absolute values and proportions. Furthermore a mean and standard error of the mean is presented. Differences in compared groups with p < 0.05 are considered statistically significant.

In average a bacteremia occurred on a 6th day of postoperative period. Frequency of the positive blood cultures was 20.7%. 972 cases of bacteremia (46.2%) was caused by Gram-positive cocci, 702 cases (33.3%) by Gram-negative bacteria and 338 (16.1%) by yeast-like fungi. Mixt-cultures were defined in 93 cases (4.4%). Monocultural bacteremia was analyzed only (n = 2012). Average level of PCT was higher (statistically significant) in cases with blood cultures than in cases without it (14.35 +/- 0.91 ng per ml vs. 7.35 +/- 0.26 ng per ml, p = 0). The highest PCT was fixed in cases of bacteremia caused by Gram-negative bacteria (26.03 +/- 2.13 ng per ml). There was no significant difference between bacteremia due to enterobacteria and non-fermenting agents (30.56 +/- 4.05 ng per ml u 22.79 +/- 0.21 ng per ml, p = 0.07). Statistically significant differences according to the average PCT were defined between bacteremia caused by Gram-negative bacteria (26.03 +/- 2.13 ng per ml), Gram-positive cocci (7.24 +/- 0.88 ng per ml, p = 0), Candida species (9.02 +/- 1.84 ng per ml, p = 0), and cases of contamination (9.92 +/- 2.79 ng per ml, p = 0). Average PCT was not significantly different in cases of bacteremia due to coagulase-negative staphylococci (5.94 +/- 0.87 ng per ml), S. aureus (4.04 +/- 0.9 ng per ml), enterococci (15.72 +/- 3.52 ng per ml), Candida species (9.02 +/- 1.84 ng per ml), in cases of contamination (9.92 +/- 2.79 ng per ml) and in cases of the negative blood cultures (7.35 +/- 0.26 ng per ml). According to ROC-analysis the optimal cut-off point for PCT as a predictor of Gram-negative bacteremia was 2.47 ng per ml, AUC 0.7 (95% DI 0.68-0.72). Index of sensitivity was 64%.

PCT level in blood plasma of patients with bacteremia higher (statistically significant) than in patients with negative blood cultures. Gram-negative infection is more likely in cases when PCT higher than 2.47 ng per ml.