Microorganisms · Published 2026-08-05 · DOI 10.3390/microorganisms14081716
Mihaela Oprea, Laura-Ioana Popa, Daniela Cristea, Sorin Dinu, Andreea Ghiță, Catherine Ragimbeau, Lavinia-Cipriana Rusu, Codruța-Romanița Usein
This study aimed to identify circulating lineages of the most prevalent human-associated <i>Salmonella</i> serotypes identified through routine surveillance in Romania between 2023 and 2025 and assess their role in the spread of antimicrobial resistance (AMR). A total of 271 isolates (217 <i>S.</i> Enteritidis, 28 monophasic <i>S.</i> Typhimurium, and 26 <i>S.</i> Typhimurium) were investigated using Illumina short-read sequencing. The isolates were assigned to 9 MLST sequence types (STs) and 109 core genome MLST complex types. The predominant STs were ST11 (96% in <i>S.</i> Enteritidis), ST19 (77% in <i>S.</i> Typhimurium), and ST34 (79% in monophasic <i>S.</i> Typhimurium). Overall, 148 isolates carried at least one AMR determinant, including 28 acquired genes and 6 gene mutations, conferring resistance to ten antimicrobial classes. Four percent of all isolates were predicted to be multidrug-resistant, often associated with determinants conferring tolerances to biocides and/or heavy metals. The most prevalent resistance markers were GyrA_D87Y in <i>S.</i> Enteritidis ST11 (94/217) and <i>bla</i><sub>TEM-1</sub> in <i>S.</i> Typhimurium ST19 (7/26). Among monophasic <i>S.</i> Typhimurium ST34 isolates, the co-occurrence of <i>bla<sub>TEM-1</sub></i>, <i>aph(3”)-Ib</i>, <i>aph(6)-Id</i>, <i>sul2</i>, and <i>tet(B)</i> genes was common (17/28). The 43 predicted AMR plasmids were not shared across serotypes, except among those carrying the <i>qnrB19</i> gene. These results provide a genomic baseline for AMR surveillance in Romania and strengthen the human surveillance component of national One Health efforts to control resistant <i>Salmonella</i>.
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Oprea, M., Popa, L., Cristea, D., et al. (2026). Genomic Insights into the Population Structure and Antimicrobial Resistance of the Most Prevalent Human-Associated Non-Typhoidal Salmonella Serotypes in Romania. Microorganisms. https://doi.org/10.3390/microorganisms14081716