Trends in incidence rates of microorganisms among patients with bloodstream infections at intensive care units in South Korea from 2011 to 2022: Data from the Korean National Healthcare-Associated Infections Surveillance System (KONIS).

Background: The trends in the microbiological distribution and incidence rates of multidrug-resistant pathogens in patients with bloodstream infections in intensive care units (ICUs) were evaluated.

Methods: This retrospective analysis was conducted using data from the Korean National Healthcare-Associated Infections Surveillance System. Annual trends in microorganism distributions and multidrug-resistant pathogens in patients with bloodstream infections (BSIs) were investigated.

Results: The incidence rate of Staphylococcus aureus infection in patients with BSIs decreased from 33.1 per 100,000 patient-days in 2011 to 9.7 in 2022. The incidence rate of BSIs due to Klebsiella pneumoniae has increased 6.4 per 100,000 patient-days in 2015 to 12.1 in 2022. The incidence rate of BSIs due to methicillin-resistant S. aureus (MRSA) [28.8/100.000 patient-days in 2011; 7.3/100,000 patient-days in 2022] and the percentage of MRSA strains [91.8% in 2011; 76.7% in 2022] decreased throughout the study period. The incidence rate of BSIs due to imipenem-resistant K. pneumoniae has significantly increased from 0.3 per 100,000 patient-days in 2011 to 6.1 in 2021, and the percentage of imipenem-resistant K. pneumoniae strains has increased from 4.3% in 2011 to 48.5% in 2022. The incidence of BSI due to imipenem-resistant Pseudomonas aeruginosa showed an increasing trend from 2011 to 2021.

Conclusion: The incidence rate of BSIs due to MRSA in the ICUs decreased, whereas the incidence rates of BSIs caused by imipenem-resistant K. pneumoniae and imipenem-resistant P. aeruginosa in the ICUs showed an increasing trend. Over the past decades, there has been a significant shift from gram-positive bacteria to gram-negative bacteria in BSIs.