A 'Tuba Drain' incorporated in sink drains reduces counts of antibiotic-resistant bacterial species at the plughole; A blinded, randomised trial in 36 sinks in a hospital Outpatients with a low prevalence of sink colonisation by antibiotic-resistant species.

Background: Multi-resistant Gram-negative bacteria (GNB) survive in hospital drains in traps that contain water and may ascend into the sink because of splashes, or biofilm growth.

Aim: To investigate whether the 'Tuba Drain' (TD) a long, bent, continually descending copper tube between the sink outlet and the trap prevents the ascent of bacteria.

Methods: After initial laboratory tests confirmed that the TD prevented bacteria in the U-bend from splashing upwards into the sink outlet, TDs were assessed in a randomised, blinded trial in a hospital out-patients built in 2019. Sinks were paired into those with a similar clinical exposure and 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. Bacterial counts in swabs from the sink outlets were determined blindly before and monthly after the plumbing change for a year. GNBs that are associated with clinical infection and carriage of resistance genes, Pseudomonas aeruginosa, Acinetobacter baumanii, Stenotrophomonas maltophilia and all Enterobacteriales spp were the organisms of primary interest and termed target bacteria.

Findings: 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 (sign test 2 tailed). Prevalence of target bacteria in sinks was low.

Conclusion: TDs were effective for reducing target bacteria in sinks.