Evaluation of the influence of the analytical characteristics of the microbiological blood study in bacteremia in a multidisciplinary hospital.

The culture method continues to be the "gold" standard for microbiological diagnosis of bloodstream infections. This is primarily due to the fact that the definition of the etiology of a generalized infectious process determines the etiotropic antibiotic therapy. To do this, it is necessary to conduct periodic microbiological monitoring of the prevailing microflora. To do this, in the present study, a retrospective analysis of the results of a microbiological blood test for sterility was performed in case of suspected bloodstream infections in a multidisciplinary hospital to assess the influence of analytical stage factors on the laboratory data obtained. Automatic hematological cultivators were used, identification was carried out based on the biochemical characteristics of microorganisms, as well as using time-of-flight mass spectrometry with matrix-activated laser desorption / ionization (MALDI-TOF MS). More than 10,000 research results were analyzed, the average microflora seeding rate was 15.1%. The analysis of the isolated microflora was carried out in 2 groups of positive results: at the beginning, the data obtained in the presence of growth in two vials at once were evaluated, then the positive results of blood cultures obtained in any one vial from a pair were studied. The predominance of gram-positive flora in the structure of microorganisms isolated from whole blood was revealed, the influence of cultivation conditions and the composition of thenutrient medium on the isolated flora was not found, however, a number of microorganisms, due to the specific characteristics of metabolism, were characterized by growth under strictly defined cultivation conditions. The presented study actualizes the need for constant microbiological monitoring in order to determine the prevailing hospital microflora, which can contribute to a timely response in order to limit the spread of highly virulent, aggressive, resistant strains of microorganisms leading to the development of generalized bloodstream infections.