Genetic Diversity, Virulence, and Antibiotic Resistance Determinants of Isolates in Romania.

The emergence of antibiotic-resistant , a leading cause of gastroenteritis worldwide, presents a significant public health challenge requiring vigilant surveillance and disease control. This study aimed to characterize strains isolated in Romania from 2017 to 2020, focusing on genetic diversity, virulence, and antibiotic resistance determinants. The isolates underwent phenotypical testing, PCR, and antibiotic resistance assessment using the Kirby-Bauer disc diffusion method for ciprofloxacin, erythromycin, and tetracycline. Genetic analysis identified resistance and virulence genes, point mutations, and performed sequence typing (7-gene MLST) to determine genetic relatedness. Results indicated substitutions at position 86 in the amino acid sequence or position 257 in the nucleotide sequence of the gene in 47 fluoroquinolone-resistant isolates. Additionally, mutations in the gene at positions 2074 and 2075, associated with macrolide resistance, were found in 12 of the 66 isolates. Allelic profiles generated 38 sequence types (STs), including three new STs not present in the reference database. The sequence data analysis revealed a genetically diverse population with a weak clonal structure. This study provides crucial insights into the genetic diversity and antibiotic resistance of strains in Romania, highlighting the need for ongoing surveillance and control measures.