Modelling environmental contamination in hospital single and four-bed rooms

Aerial dispersion of pathogens is recognised as a potential transmission route for hospital acquired infections, however little is known about the link between health care worker (HCW) contacts’ with contaminated surfaces, the transmission of infections and hospital room design. We combine computational fluid dynamics (CFD) simulations of bioaerosol deposition with a validated probabilistic HCW-surface contact model to estimate the relative quantity of pathogens accrued on hands during six types of care procedures in two room types. Results demonstrate that care type is most influential (p<0.001), followed by the number of surface contacts (p<0.001) and the distribution of surface pathogens (p=0.05). Highest hand contamination was predicted during Personal care despite the highest levels of hand hygiene. Ventilation rates of 6 ac.h−1 vs 4 ac.h−1 showed only minor reductions in predicted hand colonisation. Pathogens accrued on hands decreased monotonically after patient care in single rooms due to the physical barrier of bioaerosol transmission between rooms and subsequent hand sanitation. Conversely, contamination was predicted to increase during contact with patients in four-bed rooms due to spatial spread of pathogens. Location of the infectious patient with respect to ventilation played a key role in determining pathogen loadings (p=0.05).