Vancomycin-resistant Enterococcus faecium in a neonatal intensive care unit in Northern Italy: lessons from an outbreak and perspectives for infection control

Background: (VRE) is a major emerging pathogen, particularly concerning in neonatal intensive care units (NICUs) because of shared environments, high antibiotic exposure, and immature immune systems. Aim: To describe a four-month VRE outbreak in a level III NICU in Northern Italy and evaluate the effectiveness of containment measures. Methods: A retrospective analysis was conducted on neonates colonised with VRE between March and July 2023. Surveillance swabs, microbiological testing, and whole-genome sequencing (core genome multi-locus sequence typing [cgMLST]) were used to assess transmission dynamics. Infection control interventions included enhanced hand hygiene, patient cohorting, and environmental monitoring. Findings: Two colonisation waves were identified, with 52 of 109 neonates (48%) colonised and one case of VRE infection successfully treated. Genomic analysis revealed a clonal outbreak driven by ST80 lineage, suggesting prolonged silent transmission. A second cluster (ST18) was identified in twin neonates. The outbreak was contained through a multi-pronged approach, including active surveillance and strict infection control measures. Conclusion: This outbreak underscores the importance of vigilance and standardised protocols for VRE management in NICUs. Genomic surveillance and strict adherence to infection control practices are essential to prevent transmission in high-risk neonatal settings.