Epidemiological trends of multidrug-resistant organisms in a tertiary-care pediatric hospital, 2017–2023

BACKGROUND: Antimicrobial resistance (AMR) is a growing global threat, particularly for children under 5 years. This study is aimed to investigate temporal trends and describe the epidemiological characteristics of MDR bacteria isolated in hospitalized children from 2017 to 2023 in an academic children's hospital in Italy. METHODS: We included all bacterial isolates obtained from blood or cerebrospinal fluid (CSF) cultures collected from pediatric patients evaluated in both inpatient settings and the Emergency Department between 1 January 2017 and 31 December 2023. The study included the main ESKAPE pathogens (including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa) and other relevant MDROs such as Escherichia coli. Data were extracted from the hospital microbiology data warehouse, and resistance proportions were calculated as MDR isolates over total isolates for each pathogen. Associations between year, patient characteristics, ward type, and MDRO infections were evaluated using univariable and multivariable logistic regression; trends over time were evaluated using the Cochrane-Armitage test for categorical variables. RESULTS: Out of 51,886 blood or CSF cultures, 1,528 (2.9%) were positive for microorganisms of interest, and 211 (13.8%) were MDROs. The highest resistance proportions were observed in Carbapenems-Resistant Pseudomonas Aeruginosa/Pseudomonas Aeruginosa (CRPA/PA, 52.8%), followed by Methicilln-Resistant Staphylococcus Aureus/Staphylococcus Aureus (MRSA/SA, 36.7%), Carbapenem-Resistant Klebsiella Pneumoniae/Klebsiella Pneumoniae (CRKP/KP, 12.6%), and Vancomycin-Resistant Enterococcus (VRE)/Enterococcus (VRE/E, 11.5%). Significant reductions were recorded for MRSA/SA (43.5% in 2017 to 25.7% in 2023; p = 0.001) and CRPA/PA (85.0% to 47.1%; p < 0.001), while CRKP/KP and VRE/E showed no significant temporal trends. Neonatology and PICU showed higher odds for MRSA isolation (p < 0.001) compared to medical wards. Onco-hematology displayed an adjusted OR of 3.0 (95% CI: 1.2-7.7) for VRE. Year was independently associated with CRPA, with adjusted ORs of 0.03 and 0.14 in 2020 and 2021 (p < 0.01) compared to 2017. CONCLUSIONS: Understanding local AMR patterns remains essential for guiding empirical therapy across heterogeneous hospital settings.