The Empiric Antimicrobial Therapy: the Comparison of Initial Clinical Choice of Drugs With the Results of Microbiological Investigations - an Observational Study

Hospital infections comprise about half of all undesirable complications related to hospital treatment. In case of bacterial infection administration of antimicrobial agent is a therapy of choice. For maximum effectiveness, antimicrobial agents should be administered quickly in optimal doses. Moreover, the therapeutic concentration of properly selected drugs should be achieved as soon as possible. The relation between delays in the administration of antibiotics and increased mortality is well known. That is why proper empiric therapy is so important. Before antimicrobial investigation is completed, which may last up to 72 hours, a wide-spectrum antimicrobial should be administered according to the type of infection, its origin, and the characteristics of the local pathogens.

The objective of this study is to compare the initial choice of empiric antimicrobial therapy and the results of both microbiological identification and susceptibility/resistance analysis of isolated pathogens.

This project was designed as a prospective cohort study. Analysis was performed in a large multidisciplinary academic hospital and trauma center. All decisions on empiric therapy with antimicrobial used in infections caused by multidrug-resistant pathogens, that are made in different hospital wards except intensive care, are required by hospital procedures to be confirmed by intensivists. In our analysis, the initial choice of empiric therapy in the hospital wards other than the critical care unit was compared with the results of microbiological investigations and susceptibility/resistance analyses of isolated pathogens.

Accurate microbial identification was performed with a VITEK® 2 automatic testing system. The microbroth dilution method with VITEK® 2 AST cards was used for the antibiotic susceptibility testing of isolated pathogens.

Microbiological analyses were performed between 2018 and 2020 according to the regulations of the European Committee on Antimicrobial Susceptibility (EUCAST, version 9.0, 2019) and the National Reference Centre for Susceptibility Testing (NRCST, Warsaw, Poland).