personal items left around the sink can become contaminated , increasing the chance of transmission of pathogens to patients . Additionally , superbugs contained in sink biofilms can be flushed out of the sink into the municipal water treatment system contaminating the outside world , leading to community AMR infections . Sink design has been virtually unchanged for more than 140 years , going back to the days of Alexander Cumming and Thomas Crapper . It is time to change this plumbing .
To date , healthcare facilities have tried a wide range of interventions to stop outbreaks associated with sinks . A few of these are listed here :
● Replacing the entire contaminated sink or replacing the downpipes and p-traps .
• Still using the Crapper design , problem reoccurs soon after replacement .
● Correct defective conditions in water systems such as dead ends , low water use areas , temperature , and pressure fluctuations .
• Helpful in simplifying water flow but the P-trap is still there , maintaining the primary driver for biofilm development .
● Placement of an offset sink drain in hand hygiene sinks .
• Will reduce splashing from the sink strainer .
• P-trap is still in place allowing for biofilm growth .
● Changing to deeper sink basins to prevent cross-contamination of hands and adjacent surfaces .
• Does not eliminate splashing or biofilm growth .
● Regularly pouring disinfectants such as sodium hypochlorite , hypochlorous acid , hydrogen peroxide , acetic acid , octanoic acid , or peroxyacetic acid down sink
• Significantly decreases bioburden , but regrowth happens within a few days .
● Blocking the drain line and allowing the disinfectant to sit in the P-trap .
• More successful than just pouring disinfectant down drain .
• Regrowth will still occur .
● A device that heats and / or subjects the downpipe to ultrasound to kill and remove the biofilm .
• There will be biofilm regrowth after treatment .
Figure 3 : EasyFlow concept . Courtesy of the authors
• Units require a power source near the sink .
● Unit on sink that generates ozonated water via the faucet to disinfect the P-trap and drain at each use .
• Shown to be effective at decreasing Pseudomonas aeruginosa and Candida auris contamination .
• Due to rapid decomposition of ozone , water left to sit for long period of time in P-trap will become contaminated and form biofilms .
• Units require a power source near the sink .
• Ozone generators require engineering controls to ensure no release of ozone into occupied spaces .
It seems clear that there is no silver bullet that will eliminate the risk of pathogen ( HAI ), and particularly CRE transmission ( AMR microbes ) due to ancient design of sink P-traps and drains . Some interventions resulted in the end of outbreaks but didn ’ t fully eliminate CRE from the P-trap or drain and the potential of a CRE infection occurring . Others were not successful at eliminating the outbreak at all . We therefore propose a very different plumbing configuration to address sink biofilms and splash transmission of HAI and AMR microbes to the hospital-built environment .
EasyFlow Concept
All the interventions to date have missed the obvious , the ancient P-traps drain design is the key to biofilm development . Thus , the necessity of the immense problem lies in a new radical approach to the design called EasyFlow ( Figure 3 ). This design eliminates the P-trap . The P-trap encourages biofilm growth by simply providing the water needed to build luxurious biofilms that will harbor AMR microbes and pathogens ( HAIs ) in conditions that are hard to treat and remove . The water in the P-trap furthermore provides the necessary water of activity ( a w
) conditions in the waste lines from the P-trap to the sink strainer allowing growth of biofilm on all surfaces . Ultimately providing the source of microbes to be splashed into the hospital-built environment . Removal of the P-trap allows for reducing the a w in the sink lines such that luxurious biofilms will not form , significantly reducing the risk of splashing microbes into the hospital-built environment .
The key to EasyFlow is eliminating the P-trap . To do this an offset sink drain line is routed straight down or at any angle equal or less then 45 degrees from the bottom of the sink . After which the drain line is routed 90 o or less to the discharge line ( Figure 3 ). Sewage odors are mitigated by installing a negative pressure fan on the vent pipe to pull the air gases continually out of the entire system . Negative pressure www . healthcarehygienemagazine . com • september 2023
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