Preventing the transmission of multidrug-resistant organisms: modeling the relative importance of hand hygiene and environmental cleaning interventions

Abstract

Objective: Hand hygiene and environmental cleaning are essential infection prevention strategies, but the relative impact of each is unknown. This information is important in assessing resource allocation.

Methods: We developed an agent-based model of patient-to-patient transmission-via the hands of transiently colonized healthcare workers and incompletely terminally cleaned rooms-in a 20-patient intensive care unit. Nurses and physicians were modeled and had distinct hand hygiene compliance levels on entry and exit to patient rooms. We simulated the transmission of Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant enterococci for 1 year using data from the literature and observed data to inform model input parameters.

Results: We simulated 175 parameter-based scenarios and compared the effects of hand hygiene and environmental cleaning on rates of multidrug-resistant organism acquisition. For all organisms, increases in hand hygiene compliance outperformed equal increases in thoroughness of terminal cleaning. From baseline, a 2∶1 improvement in terminal cleaning compared with hand hygiene was required to match an equal reduction in acquisition rates (eg, a 20% improvement in terminal cleaning was required to match the reduction in acquisition due to a 10% improvement in hand hygiene compliance).

Conclusions: Hand hygiene should remain a priority for infection control programs, but environmental cleaning can have significant benefit for hospitals or individual hospital units that have either high hand hygiene compliance levels or low terminal cleaning thoroughness.

Figure 1

Panel A: Percent reduction (from the baseline) in mean Acinetobacter baumannii acquisition rates as a function of hand hygiene compliance and thoroughness of terminal cleaning. Baseline hand-hygiene compliance rates were 70% and 85% for nurses on entry and exit, respectively, and 57% and 67% for physicians on entry and exit, respectively. Baseline terminal cleaning thoroughness was 40%. Baseline prior-room occupant risk was set at 4.2. These simulation conditions produced a mean acquisition rate of 2.90 per 1000 patient days. Panel B shows mixed strategies combining hand hygiene and thoroughness of cleaning.

Figure 2

Percent reduction (from the baseline) in mean Methicillin-resistant Staphylococcus aureus and Vancomycin-resistant enterococci acquisition rates as a function of hand-hygiene compliance and thoroughness of terminal cleaning, shown with mixed strategies. Baseline hand hygiene compliance rates were 70% and 85% for nurses on entry and exit, respectively, and 57% and 67% for physicians on entry and exit, respectively. Baseline terminal cleaning thoroughness was 40%. Prior-room occupant risk was set at the experimental level of 1.8. These simulation conditions produced a mean acquisition rate of 3.88 per 1000 patient days.