A comparison of high and low level disinfection for ultrasound probes which have been used on human skin.

Ultrasound (US) contamination will be simulated through the application of US transducers on the arms of hospital staff and patients. Research team members will recruit participants as a convenience sample according to set inclusion and exclusion criteria. To control for individual patient variation in baseline skin colonisation, once participants have consented, they will be randomised into one of two groups: Group A- Right arm High Level Disinfection (HLD) & Left arm Low Level Disinfection (LLD); Group B- Right arm LLD & Left arm HLD; thereby allowing participants to act as their own control. Two identical linear US transducers will be used throughout the study, one labelled “HLD” and the other “LLD”. This will be allocated prior to study commencement and based upon which disinfection process will be repeatedly used on it. After applying 5g aliquot of sterile US gel from the same single use sachet to each transducer a research staff member will perform a mock vein localisation procedure on the arms of the recruited participant according to their group allocation. This will entail ten continuous back and forward tracing movements made on the volar and dorsal aspects of the forearm from the cubital fossa to the wrist aiming to contaminate the transducer with microorganisms. Following enrolment this process of completing a mock vein localisation procedure on recruited participants would take approximately 5 minutes in total. The same research staff member will collect the study samples from each transducer for baseline bacterial contamination. This will be determined by swabbing the area of each transducer that has encountered the participant’s skin using a standardised method involving a pre-moistened sterile cotton tip swab. Following contamination US cleaning and disinfection will occur at the point of collection by the same research staff member. Once each transducer has been reprocessed accordingly, they will be swabbed again using a sterile pre-moistened cotton tip swab. LLD will be with Clinell universal wipes ® and HLD will be with Tristel Trio wipes ® both of which have been approved by the Therapeutic Goods Administration as LLD and HLD systems respectively. To ensure that disinfection instructions are followed as per manufacture's recommendations all research staff members undertaking transducer reprocessing will be trained using manufacturer training videos in both methods of disinfection. They will also be required to demonstrate that their technique is satisfactory to the chief investigator prior to commencing any participant recruitment. Evidence of training and demonstrating a satisfactory disinfection technique will be recorded in a research training log kept by the investigator team. During training and recruitment a stopwatch will be provided at the workstation where disinfection is to occur so as to ensure that the minimum contact times of the disinfectant solutions are adhered to as per manufacturers recommendations.