Trends in incidence rates of micro-organisms 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: Trends in the microbiological distribution and incidence rates of multi-drug-resistant pathogens in patients with bloodstream infections (BSIs) 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 micro-organism distributions and multi-drug-resistant pathogens in patients with BSIs were investigated. Results: The incidence rate of BSI due to Staphylococcus aureus decreased from 33.1 per 100,000 patient-days in 2011 to 9.7 per 100,000 patient-days in 2022. The incidence rate of BSI due to Klebsiella pneumoniae increased from 6.4 per 100,000 patient-days in 2015 to 12.1 per 100,000 patient-days in 2022. The incidence rate of BSI due to meticillin-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 BSI due to imipenem-resistant K. pneumoniae increased significantly from 0.3 per 100,000 patient-days in 2011 to 6.1 per 100,000 patient-days in 2021, and the percentage of imipenem-resistant K. pneumoniae strains increased from 4.3% in 2011 to 48.5% in 2022. The incidence rate of BSI due to imipenem-resistant Pseudomonas aeruginosa showed an increasing trend from 2011 to 2021. Conclusion: The incidence rate of BSI due to MRSA in ICUs decreased, whereas the incidence rates of BSIs caused by imipenem-resistant K. pneumoniae and imipenem-resistant P. aeruginosa in 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.