Bloodstream infections – etiology and current microbiological diagnostics

Introduction: Bloodstream infections (BSI) and sepsis constitute an important clinical problem worldwide, with a high mortality rate. A fast and reliable determination of BSI etiology is necessary for administration of targeted antibiotic therapy and improvement in survival rates of patients with BSI. Aim: To present the possibilities for optimal laboratory diagnostics of BSI, in the aspect of epidemiology, available research methods and current diagnostic recommendations. Material and methods: A review of literature concerning recommendations in diagnosis and peer-reviewed publications using the following keywords ‘bloodstream infection,’ ‘bacteremia,’ ‘epidemiology,’ and ‘diagnostics.’ Results and discussion: Etiology of BSI depends on several factors, such as origin of microorganisms, the location of the primary source of infection, immunocompetence of the host, and possible contact of the patient with the healthcare. Blood culture has status of the ‘gold standard,’ which inables susceptibility testing of the isolated pathogen. Non-culture methods based on detection of microbial genetic material or proteins are increasingly used in laboratory diagnostics of BSI. They constitute the methods of choice in detection of uncultivable or difficult to culture microorganisms. New diagnostic solutions are urgently needed for rapid detection of multidrug-resistant strains of microorganisms. Conclusions: Blood culture remains the reference method in laboratory diagnostics of BSI, while molecular techniques available at present are a valuable addition to it. However, the clinical relevance of the results of molecular tests which do not correlate with clinical symptoms needs to be solved.