Clinical features and antimicrobial resistance of invasive nontyphoidal Salmonella infections in children: a single-center retrospective study

To describe the clinical characteristics, serovar distribution, and antimicrobial susceptibility profiles of pediatric invasive nontyphoidal Salmonella (iNTS) cases hospitalized at a single center. We retrospectively reviewed the clinical data of children hospitalized with iNTS at our institution from 2022 to 2025. iNTS was defined as the isolation of nontyphoidal Salmonella from blood, bone marrow, synovial fluid, or other normally sterile-site specimens. Demographic characteristics, clinical manifestations, laboratory findings, serovars, and antimicrobial susceptibility data were collected and analyzed. A total of 67 children with iNTS were included; the median age was 15 months (IQR, 10.5–27 months), and 70.1% were aged 6 months to 2 years. Disease onset showed a pronounced seasonal pattern, with 59.7% of cases occurring between July and September. Fever was present in all patients, and more than half had gastrointestinal symptoms, whereas severe focal complications, including osteomyelitis and arthritis, occurred only in a small proportion of cases. Resistance rates to third-generation cephalosporins ranged from 25.4% to 29.9%, whereas most isolates remained susceptible to β-lactam/β-lactamase inhibitor combinations, carbapenems, and tigecycline. Low susceptibility to levofloxacin was observed. Twenty-six serovars were identified, among which S. Enteritidis , S. Muenster , and S. Typhimurium were predominant. Among these small serovar groups, third-generation cephalosporin resistance was observed in 6/8 Muenster isolates and 2/7 Typhimurium isolates, whereas none of the 8 Enteritidis isolates were resistant. Pediatric iNTS in this cohort predominantly affected children aged 6 months to 2 years and clustered in summer and autumn; its nonspecific clinical manifestations continue to pose challenges for early recognition. The isolated strains exhibited diverse serovar distributions and varying degrees of resistance to certain antimicrobial agents. Clinicians should maintain heightened vigilance during peak seasons for children presenting with fever and gastrointestinal symptoms, and appropriate treatment should be guided by etiological findings and antimicrobial susceptibility testing, with favorable outcomes achievable in most cases. Not applicable.