Etiological structure of infections in patients of the surgical intensive care unit in the post -covid era

Objective.

To determine etiological structure of infections in the surgical intensive care unit (ICU), identify the most common mechanisms of antibiotic resistance of leading pathogens, and develop recommendations for optimizing antimicrobial therapy in the ICU at the present stage.

Materials and Methods.

A prospective observational study was conducted in the surgical ICU of the Moscow City Clinical Center «Kommunarka» from September 2022 to February 2024. The subjects of observation were 2120 patients treated in the unit. Microbiological examination of patients’ biological fluids was carried out in accordance with approved methodological guidelines. The results of determining the susceptibility of isolated pathogens were interpreted based on the EUCAST v14.0 criteria. Automatic bacteriological analyzers, MALDI-TOF mass spectrometry for pathogen identification, PCR and immunochromatographic methods for determining resistance mechanisms were used. To determine the etiological structure of infections in hospitalized patients, only original isolates were considered, following the principle of «one patient – one microbe.»

Results.

A total of 1213 bacterial and 53 fungal pathogens were isolated from 394 patients. The leading pathogens were Klebsiella pneumoniae (18.5%), Acinetobacter baumannii (13.4%), and Pseudomonas aeruginosa (9.5%). Resistance to meropenem was 83.0% for K. pneumoniae, 97.4% for A. baumannii, and 81.5% for P. aeruginosa. The highest in vitro activity against Enterobacterales was exhibited by ceftazidime-avibactam (79.2% of susceptible isolates), while against A. baumannii and P. aeruginosa, it was colistin (98.6% and 90.6% of susceptible isolates, respectively). The genetic mechanisms of carbapenem resistance in Enterobacterales were identified: production of NDM (26.3%), OXA-48 (29.6%), and KPC (44.1%) carbapenemases.

Conclusions.

The predominant pathogens of infections in surgical ICU patients are gram-negative bacteria with a high level of antibiotic resistance, including carbapenem-resistant Enterobacterales, whose resistance is due to the production of carbapenemases of various molecular classes. An increase in the prevalence of the serine carbapenemase KPC, previously atypical for the Russian Federation, has been noted. Currently, for infections caused by Enterobacterales producing serine carbapenemases, ceftazidime-avibactam can be recommended, and in the case of metallo-beta-lactamase production by Enterobacterales, a combination of ceftazidime-avibactam with aztreonam. For infections caused by A. baumannii and P. aeruginosa, regimens including polymyxins are indicated.