IMPLEMENTATION OF PHOSPHORIC ACID TO DECONTAMINATE CLINICAL HAND BASINS IN AN INTENSIVE CARE UNIT.

Abstract

Introduction: Clinical handbasins are an important reservoir for carbapenemase-producing organisms (CPO). Evidence-based guidance is not yet available for handbasin decontamination. We describe a novel approach for suppressing CPO colonisation of the proximal drain of handbasins within a 45-bed intensive care unit (ICU) in response to an outbreak. Method(s): We selected a phosphoric acid-based cleaning agent (Blue Thunder, Momar Australia) to suppress biofilm formation and bacterial growth. Each treatment involved pouring 250mL of the agent into the sink trap via the sink basin, 30-minute dwell time, then flushing through with water. Treatment commenced with an induction phase (2-3 times/week) followed by a maintenance phase (weekly-fortnightly treatment). We screened sink drains for CPO contamination at baseline, and intermittently thereafter. In parallel, we implemented a 'sink hygiene' campaign to discourage inappropriate disposal of liquids via handbasins. Result(s): Forty-nine clinical handbasins in 45 cubicles were included. During the first intervention period, February 2017 to April 2020, CPO-positivity declined from 80% (39/49) to 10% (5/49) (p<0.001). Treatment was ceased from April 2020 until March 2022 due to the COVID-19 pandemic. After this pause, CPOpositivity increased to 73% (36/49), before falling to 2% (1/49) (p<0.001) with decontamination resumption. Two months after commencing induction treatment, 29% (14/49) and 0% (0/49) were CPO-positive in the first and second intervention periods, respectively. Most CPO isolates were IMP-4- producing Serratia marcescens. Conclusion(s): We found that a phosphoric acid-based cleaning agent is effective in supressing CPO colonisation of clinical handbasins. Maintenance treatment was essential, with cessation resulting in relapse.