Prevalence, Clinical Characteristics and Antimicrobial Resistance Trends of Non-Typhoidal Salmonella Infections in Children: A Single-Center Study in Shanghai, China, 2014–2025

Objectives: To analyze clinical epidemiology, serogroup distribution, and antimicrobial resistance (AMR) trends of non-typhoidal Salmonella (NTS) in children to guide empirical therapy and infection control. Methods: We retrospectively analyzed 2145 pediatric NTS cases at Shanghai Children’s Hospital (2014–2025), evaluating serogroups, AMR, and multidrug resistance (MDR) trends. Results: Most patients (73.5%) were <5 years, with peak incidence in July–October (61.0%). Serogroups D (39.1%) and C (30.5%) predominated; serogroup C increased significantly over 12 years. Salmonella Enteritidis was the most common serotype (33.3%). Ampicillin resistance remained high (55.0–70.3%), and ceftriaxone resistance reached 25.8% (95/368) in 2025. One carbapenem-resistant NTS isolate was found in each of 2024 and 2025, both belonging to serogroup B. Resistance rates to azithromycin, trimethoprim–sulfamethoxazole, ciprofloxacin, and chloramphenicol were 9.8% (189/1923), 24.4% (523/2143), 9.6% (22/229), and 21.4% (97/454), respectively. Serogroup D showed high ampicillin resistance (81.2%,681/839) but the lowest MDR rate (23.5%,197/839), whereas serogroup C had the highest MDR rate (37.6%, 246/654, p < 0.001). The overall MDR rate was 30.3%. Conclusions: Pediatric NTS infections were seasonal, predominantly affecting children under 5 years. Serogroup C increased over time and carried the highest MDR burden; carbapenem-resistant NTS has emerged. Because susceptibility was classified using year-specific CLSI breakpoints, these historical trends should be interpreted alongside current local susceptibility data. Among tested isolates, serogroup D remained largely susceptible to azithromycin and trimethoprim–sulfamethoxazole.