Temporal trend and individual and hospital characteristics associated to vancomycin-resistant Enterococcus faecium bloodstream infections: a retrospective analysis from the national surveillance system, Italy 2015-2023.

Background: Several countries have reported an increase in vancomycin-resistant Enterococcus faecium (VREF), a pathogen classified by the WHO as a high-priority threat due to its role in healthcare-associated infections and in-hospital mortality. This study aimed to describe temporal trends in VREF bloodstream infections in Italy from 2015 to 2023 and to explore patient and hospital characteristics associated with VREF.

Methods: We conducted a retrospective observational study using data from the Italian national antimicrobial resistance surveillance system (AR-ISS). All E. faecium bloodstream isolates tested for vancomycin resistance between 2015 and 2023 were included in the trend analysis. To examine associations with individual (sampling year, season, sex, age group, hospital unit, and geographical area) and hospital-level (number of beds, average length of stay, turnover index, bed occupancy rate, and turnover interval) characteristics, we focused on hospitalized adults (≥ 18 years) from 2022 to 2023. Mixed-effects logistic regression models were used to estimate trends and assess associations, with hospitals included as a random effect.

Results: Among 29,050 E. faecium isolates, the proportion of VREF rose from 11.5% in 2015 to 32.4% in 2023. Central Italy recorded the highest resistance in 2023 (44.8%), while the South and Islands showed the steepest relative increase (from 1.8% to 29.4%). In the 2022-2023 dataset, multivariable analysis showed higher odds of VREF among patients aged 40-79 years (versus ≥ 80 years; OR = 1.18, 95% CI: 1.02-1.38), those admitted to medical units (versus surgical units; OR = 1.18, 95% CI: 1.03-1.36), and in hospitals with more than 400 beds (versus < 400 beds; OR = 1.31, 95% CI: 1.09-1.58) or an average length of stay exceeding 10 days (versus ≤ 10 days; OR = 1.34, 95% CI: 1.07-1.69).

Conclusions: This study reveals a persistent increase in VREF bloodstream infections in Italy from 2015 to 2023. The findings highlight significant regional disparities and hospital characteristics linked to higher resistance rates, emphasizing the need for coordinated national and regional strategies. Strengthening integrated surveillance, antimicrobial stewardship, and infection prevention is essential to mitigate this growing public health concern.

Trial registration: Clinical trial number: not applicable.