Changes in the microbial spectrum and antimicrobial resistance of bloodstream infections in intensive care units before and during the COVID-19 pandemic
Year: 2026
Type: article
Study design: Observational Study
Abstract: Bloodstream infections (BSIs) are major infectious conditions associated with high morbidity and mortality, particularly in intensive care units (ICUs). In critically ill patients, early and appropriate empirical antimicrobial therapy plays an important role in preventing adverse clinical outcomes. However, the increasing burden of antimicrobial resistance necessitates that empirical treatment strategies be continuously reassessed based on up-to-date local resistance data. This study aimed to compare the distribution of bacterial pathogens and antimicrobial resistance profiles of BSIs identified in ICUs before and during the coronavirus disease 2019 (COVID-19) pandemic. A total of 388 patients diagnosed with BSIs while hospitalized in the ICUs of Health Sciences University Prof. Dr. Cemil Taşçıoğlu City Hospital between March 2019 and April 2021 were retrospectively evaluated. During the pandemic period, patients with and without COVID-19 were analyzed together without stratification. Bacterial isolates recovered from blood cultures and their antimicrobial susceptibility results were compared between the pre-pandemic and pandemic periods. Multivariable analysis identified independent risk factors for multidrug resistance (MDR) in Klebsiella pneumoniae , adjusting for clinical confounders. Pre-pandemic, the predominant pathogens were K. pneumoniae (30.1%), A. baumannii complex (21.9%), and S. aureus (9.7%); during the pandemic, K. pneumoniae (34.4%), A. baumannii complex (21.2%), and E. faecium (10.4%) led the distribution. During the pandemic, non-fermentative Gram-negative bacilli showed a significant increase in ceftazidime resistance, while resistance to amikacin, gentamicin, and meropenem declined. In Enterobacterales, extended-spectrum beta-lactamase (ESBL) production and carbapenem resistance increased during the pandemic. In K. pneumoniae , while carbapenem resistance remained statistically stable, colistin resistance increased significantly, raising a new concern. Prior antimicrobial therapy was the sole independent predictor of MDR in K. pneumoniae (adjusted Odds Ratio [aOR] = 8.296, 95% Confidence Interval [CI] = 1.471–46.794, p = 0.017). During the COVID-19 pandemic, Gram-negative pathogens continued to predominate among BSIs identified in ICUs, with an observed trend toward increased antimicrobial resistance, particularly among Enterobacterales species. Notably, prior antibiotic exposure was identified as the key independent determinant of MDR status in K. pneumoniae. Given the dynamic nature of pathogen distribution and resistance profiles in BSIs, consideration of local and period-specific resistance patterns in ICU settings may help inform empirical antimicrobial treatment strategies. Not applicable.
Source: BMC Infectious Diseases
Institutions: Ministry of Health, Sağlık Bilimleri Üniversitesi
Language: English
Subfield: Molecular Medicine
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,090
OpenAlex ID: W7170957171
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