INFECTION PREVENTION AND CONTROL
Above left: Figure 2. This is the standard drain system used in the Outpatients’ Department. Note the flexible blue antimicrobial waste pipe. When Tuba Drains were included they were inserted between the blue waste pipe and the U-bend. Above right: Figure 3. A front view of the Tuba Drain.
The usual approach to hospital sink drainage is obviously flawed. Water exiting the sink falls from a height directly into a pool of contaminated water in the U-bend or trap, causing contaminated splashes to contaminate the sink outlet.3
Some sinks even have taps which direct a jet
of water directly into the plughole, which is extremely bad design.
James Soothill
Dr James Soothill MBBS, MD, FRCPath, has worked as a Consultant Microbiologist at Great Ormond Street Hospital for Children in London for the past 25 years. His work includes advising on the prevention, diagnosis, and management, of hospital infection, and his interests include measures to control the transmission of antibiotic-resistant bacteria, including the use of probiotics and bacteriophages to control gut carriage. He initiated a pioneering treatment at Great Ormond Street Hospital using Genetically modified bacteriophage that received widespread media coverage. He reports that his work to prevent central venous catheter-associated infections via the use of chlorhexidine wipes on line ports reduced the number of infections to one-third of what it had been, ‘with a huge financial saving’.
n Tuba Drain A simple solution to the problem is the Tuba Drain.4
This
is simply a bent length of pipe made of an antimicrobial material that descends throughout its length. The inlet of the Tuba Drain includes a slope of changing gradient (the ski-jump slope) that redirects the water with minimum splashing. Any splashing that does occur is not from a pool of contaminated water, as there is no pool where the water is landing. While the Tuba Drain is designed to fully drain, and therefore dry (drying kills many of the key bacteria), and is also made of antibacterial copper, it would be possible for a layer of bacteria to grow on its surface. In that event it would be possible to kill the bacteria simply by heating the Tuba Drain in situ using an electric heat gun of the sort used for stripping paint. In very high risk areas this could be a regular treatment of Tuba Drains. Copper is a good conductor, and is heat- resistant, and the length of the TD ensures that its ends could be not so hot as to damage plastic connected to them.
Lab and hospital testing The TD has been demonstrated to be effective both in the laboratory and in a hospital Outpatients’ Department. A laboratory assessment was made of the TD using drain components that were not attached to a sink, to investigate whether it prevented splashes from reaching a point just downstream of the sink outlet. A 35 mm diameter brass compression fitting was
attached to the top of a brass bottle trap; then 3.5 ml of a broth culture of bacteria was added to the bottle trap through its outlet. A 60 mm long 35 mm outer diameter sterile copper tube was then attached to the compression fitting. The non-draining part of the trap was filled with water from its inlet. After filling the trap a cold tap was then run full on for 10 seconds into the top of the copper pipe. The luminal surface was swabbed to sample any bacteria present. The pipe was disconnected, and culture added, after which the TD was attached to the compression
42 Health Estate Journal August 2025
fitting. The tap was run as above into the top of the TD. The internal lumen of the top of the TD was swabbed to a depth of 10 cms (the free length of the swab) to sample any bacteria present. The process above was then repeated a further 7 times. 8/8 swabs from the 60 mm pipes and 0/8 of those from the TD grew the strain of bacteria that had been added to the traps p=0.002. The result of this study was as expected. Bacteria
splashed upwards with normal plumbing, but the Tuba Drain prevented this from happening in all cases. While this is an obvious advantage, we also tested the function of the Tuba Drain in an Outpatients’ Department in a blinded, randomised trial. Bacteria that are associated with clinical infection and antibiotic resistance were the organisms of primary interest, and termed ‘target bacteria’. Those were the bacteria that we decided to study, before the start of the trial. Sinks were paired into those that we judged would have a similar risk of colonisation by the resistant bacteria we were studying. This related primarily to the type of use of the sinks. Each member of each pair was randomised to receive either new, standard plumbing up to and including the trap (18 sinks), or the same new standard plumbing, but including the TD inserted between the sink outlet and trap. Counts of target bacteria in swabs from the sink outlets were determined blindly before and monthly after the plumbing change for a year. The TDs fitted into the required spaces, and functioned without problems. The geometric means (over months) of the counts of target bacteria in TD-plumbed sinks was lower than those in their paired controls p= 0.012. The Tuba Drains remained in Outpatients’ for a further year, and during the two years of their use there were no problems, and no maintenance needed.
Preventing the ascent of splashes The TD prevents the ascent of splashes from the trap, including those containing antibiotic-resistant bacteria. The design slopes downwards throughout its course, which facilitates drying when not in use. As the Gram- negative bacteria that colonise traps are killed by drying, this is a helpful feature for preventing the formation of surface films of bacteria (biofilms), as is the use of antimicrobial copper. The sinks used were Ideal Standard Contour sinks fitted with a wide flexible waste pipe which included
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