Genomic and plasmid profiles of multidrug-resistant <i>Salmonella</i> isolates from pediatric patients from Zhuhai, China

Multidrug-resistant <i>Salmonella</i> has been classified as a pathogen of high priority. However, limited or mixed-quality studies reported multidrug-resistant <i>Salmonella</i> strains from pediatric patients. The study aimed to investigate the prevalence, serotypes, antimicrobial characteristics, and plasmid profiles of clinical <i>Salmonella</i> strains isolated from pediatric patients. For that, we collected 46 <i>Salmonella</i> isolates from children's fecal samples in multiple hospitals. Antimicrobial susceptibility testing, conjugation assay, short-read and long-read sequencing, and bioinformatics analysis were performed. Our data revealed that the top three serotypes of the 46 isolated strains are <i>Salmonella</i> I 4,[5],12:i:-, Typhimurium, and Enteritidis, with prevalence at 34.78% (16/46), 23.91% (11/46), and 17.39% (8/46), respectively. Most of these strains clustered into ST34, ST19, and ST11. Antimicrobial susceptibility testing analysis suggested that more than 80% of these <i>Salmonella</i> isolates belong to multidrug-resistant strains, all of them showed resistance to ampicillin, ampicillin-sulbactam, and trimethoprim-sulfamethoxazole, and all strains were susceptible to meropenem, with about 17.39% of them having minimum inhibitory concentrations ≥4 µg/mL to imipenem. Moreover, conjugation assay and long-read sequencing analysis on the plasmids harbored in 12 of the 46 <i>Salmonella</i> strains consistently showed that none of them has intact conjugative transfer genes, indicating <i>Salmonella</i> strains from pediatric patients have different antimicrobial resistance levels and impaired plasmid transferability due to loss of part or whole <i>tra</i> genes.IMPORTANCE<i>Salmonella</i>, one of the world's top prevalent foodborne pathogens, has gained resistance to fluoroquinolone and many other drugs that are used clinically. However, few studies focused on the genomic and plasmid profiles of multidrug-resistant <i>Salmonella</i> isolates from pediatric patients. In the present report, our data indicate that <i>Salmonella</i> strains isolated from pediatric patients have different antimicrobial resistance levels and plasmid transferability compared to those from adults. These findings provide crucial insights into pediatric patients' isolated <i>Salmonella</i> strains from Zhuhai, China, which can be leveraged to optimize drug regimens, leading to more effective and less toxic treatments for pediatric infections, and call for more attention to <i>Salmonella</i> epidemiology and antimicrobial resistance patterns in children.