Background: Healthcare-associated infections (HAIs) present a significant global burden, with resistant pathogens such as vancomycin-resistant enterococci (VRE) being of particular concern. Dry surface biofilms (DSBs) have recently emerged as critical reservoirs for multi-drug-resistant organisms in healthcare environments, yet little is known about enterococcal DSB formation and persistence.
Aim: This study aimed to evaluate the ability of various Enterococcus species and clinical isolates to form DSBs on healthcare-relevant materials, assess their long-term survival, and explore factors influencing DSB culturability.
Methods: Multiple enterococcus strains, including epidemic and vancomycin-resistant isolates, were cultured using a standardized DSB formation model on a range of surfaces and materials commonly found in healthcare settings. Culturability was assessed through serial dilutions and colony enumeration. Structural characterization was performed via scanning electron microscopy (SEM), confocal microscopy and flow cytometry.
Findings: All enterococcus strains formed DSBs on stainless steel and other clinical materials. DSBs maintained high culturability (5-6 log10) for up to 84 weeks at 20 °C and 55% relative humidity. VRE strains exhibited lower culturability compared with non-VRE. No correlation was found between DSB formation and surface roughness or hydrophobicity. SEM, confocal imaging and flow cytometry confirmed heterogeneity in DSB structure and viability across surfaces.
Conclusion: Enterococcus spp. can form persistent, viable DSBs on diverse healthcare surfaces, contributing to the environmental persistence of pathogens. The combination of mechanical removal with an effective disinfectant remains at present the best approach for DSB control on hard surfaces. As such, enhanced cleaning and disinfection might be, for the time being, the best approach to control DSBs on hard surfaces.
Keywords: DSB; Enterococcus; Persistence; Surfaces; Viability.
Copyright © 2025. Published by Elsevier Ltd.