subsp. Harboring ST233, ST1263, and ST1845 in Children.

Objective: This study aims to analyze the molecular epidemiology, resistance, and pathogenicity of subsp. isolated from children.

Methods: Whole genome sequencing was carried out, and molecular serotypes, sequence types, resistance genes, and virulence genes of subsp. isolates were analyzed. Antimicrobial susceptibility test was determined by commercialized microdilution method.

Results: A total of three isolates of subsp. were isolated during 2015 to 2020. The molecular serotypes of the three strains were 61:c:z35, 61:l,v:1,5,7:[z57], and 65:k:z, respectively, and the sequence types were ST1845, ST233, and ST1263. All the three isolates were susceptible to ceftriaxone, ceftazidime, cefepime, amoxycillin/clavulanic acid, piperacillin/tazobactam, ertapenem, imipenem, levofloxacin, and trimethoprim/sulfamethoxazole. No other resistant gene was detected except . There were no resistant plasmids detected in all the three isolates. A total of 76 genes were present in all isolates, containing 49 genes of Type III Secretion System (T3SS) mediated by SPI-1and SPI-2, 13 genes of adherence (type 1 fimbriae, Agf, and MisL-related genes), 11 genes of iron uptake (Yersiniabactin), two genes of magnesium uptake, and one gene of typhoid toxin().

Conclusion: The serotypes and sequence types of subsp. isolates were rarely reported in children; all the subsp. isolates were susceptible to detected antibiotics; T3SS, adherence, iron uptake, magnesium uptake, and typhoid toxin were responsible for pathogenicity of the subsp. isolates in children.