Urinary Tryptophan Metabolites, Trace Element Status, and Autism Spectrum Disorder: An Integrated Metabolomics-Elementomics Study in Children.

Healthcare-associated infections (HAIs) remain a significant public health problem, associated with increased morbidity and mortality, prolonged hospital stays, and a significant rise in costs within the hospital setting (). Despite the progress made in recent decades in terms of infection prevention and control strategies, the incidence of HAI remains high, particularly in hospital settings, where clinical complexity, exposure to invasive procedures and the coexistence of multiple risk factors increase the vulnerability of inpatients (, ). The identification and monitoring of infection risk play a central role in infection prevention and control programmes, enabling support for clinical decision-making and the timely implementation of preventive interventions targeted at higher-risk groups. International recommendations emphasise the importance of epidemiological surveillance based on systematic and structured approaches, capable of generating comparable and useful data for the continuous improvement of the quality and safety of healthcare (World Health Organization, 2016; Organisation for Economic Co-operation and Development, 2019). However, in many clinical settings, the assessment of infection risk remains largely unsystematic, hindering the epidemiological characterisation of risk at institutional and national levels (). Furthermore, recent literature reviews and leading international reports identify significant gaps in knowledge regarding the distribution of infection risk and its associated factors in hospital populations, highlighting the need for up-to-date, standardised and context-specific prevalence studies capable of capturing variability between institutions and regions and of supporting epidemiological surveillance and the planning of prevention strategies (, ). Despite the growing body of scientific literature in this area, the available evidence has significant limitations. Most studies focus on the prevalence of established infections, with less emphasis on the prospective and systematic assessment of the risk of infection in hospitalised patients. Furthermore, many studies feature single-centre designs, methodological heterogeneity and a lack of validated tools for risk stratification, hindering the comparability of results and the generalisation of conclusions (, ). Recent reviews have also highlighted the scarcity of studies that simultaneously integrate intrinsic and extrinsic individual factors, as well as organisational variables, into the analysis of infection risk, highlighting the need for multicentre research using standardised methodologies and robust risk assessment tools (, ).