Comparative Analysis of Antimicrobial Resistance Patterns between Blood and Non-blood Clinical Isolates in a Korean Tertiary-care Hospital

This study compared the specimen-type-specific antimicrobial resistance (AMR) patterns of major clinical bacterial isolates in Korea to provide baseline data for empirical antibiotic therapy.A total of 19,188 isolates were obtained from 17,242 patients between 2021 and 2023 at a tertiary hospital in the Gyeonggi region, including 1,484 and 17,704 from blood and non-blood specimens, respectively.The predominant organisms were Staphylococcus epidermidis (40.7%) and Escherichia coli (33.1%) in the blood and nonblood samples, respectively.Notable resistance was observed in Klebsiella aerogenes (imipenem 14.3%), Enterococcus faecalis (high-level gentamicin 40.3%),Enterococcus faecium (ampicillin 92.7%; vancomycin 42.5%), S. epidermidis (penicillin G 83.9%; oxacillin 82.1%), and Streptococcus pneumoniae (clindamycin 85.7%; erythromycin 93.7%), with significantly higher rates in blood isolates (P<0.05).Compared to the KOR-GLASS 2023 surveillance data, Pseudomonas aeruginosa showed slightly higher piperacillin resistance (31.8% vs. 28.1%),but the difference was not statistically significant (P>0.05).Modest increases were also observed for MRSA (53.0%),VRE (42.5%), and S. pneumoniae (erythromycin 93.7% vs. 94.6%nationally).These findings highlight distinct AMR trends between blood and non-blood isolates and indicate continuous selection pressure in tertiary-care settings.Ongoing regional surveillance and specimen-type-based antimicrobial stewardship are essential to enhance empirical therapy and support national AMR management in Korea.