Distribution of Extended-Spectrum-β-Lactamase-Producing Diarrheagenic Clonal Complex 10 Isolates from Patients with Diarrhea in the Republic of Korea.

ESBL-producing is a public health concern in healthcare settings and the community. Between 2009 and 2018, a total of 187 ESBL-producing pathogenic isolates were identified, and clonal complex (CC) 10 was the predominant clone ( = 57). This study aimed to characterize the ESBL-producing pathogenic CC10 strains obtained from patients with diarrhea to improve our understanding of CC10 distribution in the Republic of Korea. A total of 57 CC10 strains were selected for comprehensive molecular characterization, including serotype identification, the analysis of antibiotic resistance genes, the investigation of genetic environments, the determination of plasmid profiles, and the assessment of genetic correlations among CC10 strains. Among the CC10 isolates, the most prevalent serotype was O25:H16 ( = 21, 38.9%), followed by O6:H16 (10, 19.6%). The most dominant ESBL genes were ( = 31, 55%) and ( = 15, 27%). Most genes ( = 45, 82.5%) were located on plasmids, and these incompatibility groups were confirmed as IncB/O/K/Z, IncF, IncI1, and IncX1. The mobile elements located upstream and downstream mainly included (complete or incomplete) and or . Phylogenetic analysis showed that the CC10 strains were genetically diverse and spread among several distinct lineages. The results of this study show that ESBL-producing pathogenic CC10 has been consistently isolated, with CTX-M-15-producing O25:H16 isolates being the major type associated with the distribution of CC10 clones over the past decade. The identification of ESBL-producing pathogenic CC10 isolates underscores the possible emergence of resistant isolates with epidemic potential within this CC. As a result, continuous monitoring is essential to prevent the further dissemination of resistant ESBL-producing CC10 strains.