[EXPRESS IDENTIFICATION OF POSITIVE BLOOD CULTURES USING DIRECT MALDI-TOF MASS SPECTROMETRY].

OBJECTIVE: To evaluate the effectiveness of direct identification of pathogens of bacteremia by direct matrix assisted laser desorption ionization time-flight mass spectrometry (mALDI-TOF) compared to routine method. MATERIAL AND METHODS: A prospective study included 211 positive blood cultures obtained from 116 patients (106 adults and 10 children, aged from 2 weeks to 77 years old in the ICU after open heart surgery. Incubation was carried out under aerobic vials with a sorbent for antibiotics Analyzer BacT/ALERT 3D 120 (bioMerieux, France) in parallel with the primary sieving blood cultures on solid nutrient media with subsequent identification of pure cultures using MALDI-TOF mass spectrometry analyzer Vitek MS, bioMerieux, France routine method), after appropriate sample preparation we carried out a direct (without screening) MALDI-TOF mass spectrometric study of monocomponental blood cultures (n = 201). RESULTS: using a routine method in 211 positive blood cultures we identified 23 types of microorganisms (Staphylococcus (n = 87), Enterobacteria- ceae (n = 71), Enterococci (n = 20), non-fermentative Gram-negative bacteria (n = 18), others (n = 5). The average time of incubation of samples to obtain a signal of a blood culture growth was 16.2 ± 7.4 h (from 3.75 to 51 hours.) During the first 12 hours of incubation, growth was obtained in 32.4% of the samples, and on the first day in 92.2%. In the direct mass spectrometric analysis mnonocomponental blood cultures (n = 201) is well defined up to 153 species of the sample (76.1%), while the share of successful identification of Gram-negative bacteria was higher than that of Gram-positive (85.4 and 69, 1%, respectively p = 0.01). The high degree of consistency in the results of standard and direct method of identifying blood cultures using MALDI-TOF mass spectrometry (κ = 0.96, p < 0.001; the samples included in the calculation for which both option given result). Duration of the direct mass spectrometric analysis, including sample preparation, was no longer than 1 hour: CONCLUSION: The method of direct MALDI-TOF mass spectrometry allows to significantly speed up the identification of blood cultures that may contribute as much as possible early appointment effective regimes of starting antibiotic therapy.

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

PURPOSE OF THE STUDY: To define diagnostics ability of procalcitonin (PCT) test for prediction of bacteremia of different etiology in cardio-surgical patients. MATERIALS AND METHODS: 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. RESULTS: 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%. CONCLUSIONS: 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.

[The express mode of identification of agents of bacteriemias using the technique of gas chromatography-mass spectrometry].

The comparative evaluation was carried out concerning the effectiveness of generic identification of hemocultures using the technique of gas chromatography-mass spectrometry by comparison with data of common cultural method. The content of vials with positive hemoculture was analyzed using both the common microbiologic methods and the technique of gas chromatography-mass spectrometry with detection of markers of the most widespread agents of nosocomial bacteriemias: microorganisms of genus Staphylococcus, Enterococcus, Klebsiella, Escherichia, Serratia, Pseudomonas, Acinetobacter, Stenotrophomonas, Candida. The possibility of applying the technique of gas chromatography-mass spectrometry for generic express-identification of agents of bacteriemias was established. The full concurrence of results obtained by gas chromatography-mass spectrometry with the results of common bacteriologic method was revealed. The time saving of analysis during generic identification of hemocultures using gas chromatography-mass spectrometry up to three and less hours against 1.5-2 days in case of common approach. The established information can input into earlier start of etiotropic therapy under severe infections.