Analysis of the Structure of Bacteremia and Sensitivity to Antibiotics of Microorganisms Isolated in Intensive Care Units in an Emergency Hospital in the Period from 2003 to 2021: a Retrospective Observational Study

INTRODUCTION: Creation of protocols for effective empiric antimicrobial therapy is impossible without the analysis of current antibiotic susceptibility data. OBJECTIVE: Analysis of changes in the etiological significance of the leading pathogens of bacteremia in the ICU (intensive care unit) in the period from 2003 to 2021, and their sensitivity to antibiotics; study of the types of carbapenemases in the most relevant pathogens — Klebsiella pneumoniae and Acinetobacter baumannii. MATERIALS AND METHODS: The analysis included all microorganisms isolated from the blood of patients who were in the medical 12-bed ICU in the emergency hospital of Moscow in the period from 2003 to 2021. Identification of microorganisms and determination of antibiotic sensitivity were carried out with an automatic PHOENIX analyzer and a standardized disco diffusion method. Detection of carbapenemases was carried out by PCR (polymerase chain reaction). RESULTS: In the period from 2003 to 2021, 17 034 blood samples were examined, from which 6372 microorganisms were isolated. During this period, the proportion of Gram-negative microorganisms increased from 21.0 to 52.8 %, mainly due to K. pneumoniae from 1.0 to 24.5 % and A. baumannii from 0 to 9.1 %. The resistance of these microorganisms to carbapenems increased significantly from 2008 to 2021: K. pneumoniae from 2.3 % to 70.3 %, A. baumannii — from 7.5 to 99.5 %. K. pneumoniae produced the following types of carbapenemases: OXA-48 (73.8 %), KPC (6.2 %), NDM 1.5 %, NDM + OXA-48 (15.4 %), KPC + OXA-48 (3.1 %). All A. baumannii strains produced OXA-40 type carbapenemase. OXA-48 carbapenemase producers were resistant to colistin and tigecycline in 14.6 and 44.8 %, and to ceftazidime/avibactam in 4.2 %. CONCLUSIONS: The increased level of antimicrobial resistance in recent years among Gram-negative microorganisms isolated from blood is a very significant problem in the ICU. Most K. pneumoniae strains are characterized as multi-drug resistant, about 10 % of the strains were categorized as extremely-drug resistant (XDR) or pan-drug resistant. All strains of A. baumannii belong to the category of XDR.