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Sarah S. Lewis et al
Table 1. Potential Strategies to Mitigate Transmission of Pathogens from Contaminated Sink Drains
Type of Intervention
Behavioral modifications to minimize drain colonization
Engineering modifications to minimize contamination of surrounding surfaces
Examples First Line Strategies Appropriate for All Settings
∙ Separation of clean and dirty tasks
∙ Splash guards/ barriers
∙ Dedicated storage space >1m from sinks
∙ Sink design to reduce splashes
Fig. 1. Diagram of a hospital sink drain.
hospital rooms have clinical sinks (ie, hoppers) dedicated for waste disposal and separate from hand washing sinks. However, in our experience, clinical sinks are not present in all acute-care hospital rooms, and it is common practice for clean and dirty activities, including hand hygiene and waste disposal, to occur in the same in-room sink. Together with properties of sinks that promote colonization and biofilm formation and the proximity of sinks to patient care equipment and room surfaces, this creates a high-risk situation that is underrecognized in most acute-care hospitals.
Potential Mitigation Strategies
Numerous chemical disinfectant strategies have been trialed to disinfect colonized drains with limited success.3,7,13–15 Biofilms in wastewater plumbing systems are relatively resistant to dis- infectants and are not easy to access. Furthermore, disinfectants poured down the drain are diluted by water in the P trap and do not achieve recommended dwell times. Although this can be overcome by blocking, disinfecting, and then draining sinks simultaneously, this approach is logistically challenging and impractical in the long term. Finally, repeated use of corrosive chemicals may lead to degradation of plumbing over time. For all these reasons, strategies to mitigate colonization and/or prevent transmission from colonized drains are needed (Table 1).
Engineering Modifications to Reduce Transmission from Colonized Sinks
Sink design
Ideally, the risk of transmission of pathogens from sink drains to patients could bemitigated through better sink design. Gestrich et al8 evaluated the association between sink characteristics and dispersion of fluorescent tracer outside the sink bowl in 171 sinks from 4 hospitals. The following sink characteristics were evaluated: depth of sink bowl, diameter of sink bowl, location of faucet relative to strainer (directly over vs offset), distance from faucet to strainer, distance from strainer to sink edge, automatic versus manual operation, and type of material. Of these characteristics, only sink
Secondary Strategies for Mitigation or High-Risk Settings
Engineering modifications to minimize dispersion from contaminated drains
Engineering modifications to eliminate biofilm formation
∙ Drain covers ∙ Hopper covers
∙ Requires routine cleaning and maintenance; long- term benefit and feasibility unproven
∙ Heater vibrator units
∙ Ozonated water
∙ Costly; long-term benefit and feasibility unproven
∙ Limitations of physical space or workflow may make this challenging
∙ Consider during design phase for building and remodeling
Notes
bowl depth was associated with dispersion of the gel outside the bowl, with dispersion occurring in nearly half of sinks with depth ≤19cm and rarely when depth exceeded 24cm.8 Additionally, there are important dynamics between water flow rate and pathogen dispersion that may not be fully mediated by sink design and must be balanced with functionality and the risks of low-flow states.
Modifications to minimize contamination of surrounding objects
Engineering modifications including appropriate use of splash guards and well-designed medication preparation and supply sto- rage areas away from sinks and drains are important interventions to limit contamination of medications and supplies that are sub- sequently used for patient care. Hota et al13 reported a prolonged outbreak of multidrug-resistant Pseudomonas infections among ICU patients linked to imperfect ICU room design in which handwashing sinks were adjacent to open countertops used for medication preparation. The outbreak was ultimately mitigated when the in-room sinks were closed and remodeled, including installation of a barrier between sinks and adjacent storage areas and ensuring that no patient care items were stored within 1m of the sink.13 Despite evidence to support physical separation of sinks from adjacent countertops and storage areas, such safeguards are not recommended in guidelines or mandated by building code requirements for newly constructed hospital buildings.16
Modifications to minimize dispersion from contaminated drains
Drain covers that allow passage of water but prevent backsplash and dispersion are straightforward interventions with potential
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