Vetnuus | October 2024 21 The need for meaningful measurement In these days of antimicrobial resistance (AMR), where only the ‘responsible peri-surgical antibiosis’ is permitted there has to be a greater focus on hygiene, and the prevention of nosocomial infection, together with the control of zoonotic and pandemic risks, to staff, clients and veterinary patients. Until now the assessment of cleanliness has relied upon visual assessment, despite the fact that for many years it has been accepted that visual assessment alone is unreliable (Malik et al 2003). Malik reported that ‘visual assessment yielded 90% pass’, ‘microbiology 10% pass’, ‘ATP 0% pass’, putting the inadequacy of visual assessment into context. Burgess and Morley (2015), have reminded us that ‘one cannot manage what one does not measure’, and the RCVS PSS, now requires participating practices to measure infection control outcomes. There has for many years been controversy and debate between microbiology and Adenosine Tri Phosphate (ATP). Whilst microbiology specifically measures the numbers of colony-forming units (for a given measured area), in contrast, ATP bioluminescence measures organic residue levels, i.e. microbes, animal material, plant material, biofilms (however, not viruses). Some workers state that it is the microbes’ presence on a surface which constitutes the risk of nosocomial infection (hence microbiology is most applicable), whilst others suggest that ‘testing for the efficacy of sanitisation and assessing the potential for microbial proliferation’, ATP is more appropriate, as any residual ‘animal or plant material’ indicates that the surface has not been adequately cleaned, the presence of microbes (bacteria and fungi), speaks for itself, whilst measuring biofilms is relevant to the risk, of poor hygiene. Biofilm A biofilm is defined as ‘a community of microorganisms adhering to a surface and surrounded by a complex matrix of extra-polymeric substances’ (Bridier et al (2011). It is accepted that the biofilm growth mode induces microbial resistance to disinfection, which results in substantial economic and health concerns. Bridier et al report that 80% of microbes are found in the biofilm and that microbes in a biofilm are 1000x more resistant to the effects of disinfectants and antibiotics. Parvin et al (2019), have shown that >90%, of dry surfaces in human ICUs are covered in biofilm, moreover that even after fifty wiping motions with a cloth, only 96.7% of biofilms have been removed, showing how challenging it is to wipe away a biofilm from a dry surface. Such biofilms on dry surfaces are shown to remain viable for in excess of 12 months. If a biofilm residue is left on a surface, it provides a nutritious medium for microbial growth and acts as a barrier to the direct action of both cleaners and disinfectants. Microbiological vs ATP bioluminescence measurements Conventional microbiological methods detect only microorganisms and can take 48 - 120 hours for results, in contrast, ATP measures organic material residue (including microbes), the cost per swab being perhaps 1/20th of microbiology with results being available, on-site, in 10 seconds. (ATP bioluminescence is not currently a standardized methodology: each ‘Relative Light Unit’(RLU) reader has different benchmark values, not always clearly defined, such that a result with one manufacturer’s reader is not necessarily comparable with others, thus there is an advantage for operators working in a given field or discipline to utilise the same readers as each other, such that results are comparable). ATP testing has been shown to improve cleanliness standards on healthcare surfaces where feedback from the testing is timely and continuous, particularly when regularly applied to potential fomite locations (Mitchell et al 2020, Chan et al 2015). ATP testing has been recognized by the CDC as an objective way to appraise cleaning effectiveness in hospital settings and was recommended to the CDC by their Hospital Epidemiology Committee (CDC 2019). Other research trials (Kim et al 2023, Singaravelu et al 2023), used ATP effectively, for the detection of recurrent reservoirs (typically fomites) of specific infections in human and veterinary hospitals, demonstrating an ability to detect, quantify and the origins of repeated contamination. ATP testing has been shown to improve cleanliness standards on healthcare surfaces where feedback from the testing is timely and continuous, particularly when regularly applied to potential fomite locations (Mitchell et al 2020, Chan et al 2015). Test model and protocol Methods Prior to intervention, where both existing cleaning and disinfection products and procedures were in use approximately forty-eight swabs were collected (unannounced, before the working day commenced) at three UK veterinary facilities, from common and standardised locations, (using Hygiena Ensure ATP system), to quantify the level of contamination as shown in the Baseline results in Table 1. Thereafter a single (45-minute) staff ‘hygiene control’ training session was given to as many staff of all roles, as each practice could muster on their chosen day. A standardised optimal cleaning system (using a proprietary biofilm remover at the start), followed by a proprietary disinfectant cleaner, prior to terminal disinfection, delivered by ‘fogging’), was introduced into all three sites. The standardised swab locations were retested (using identical methodology) in each facility, on average 70 days later. The veterinary facilities were all small animals, each owned by different corporate, first opinion practices ranging in size from 3-6 vets. A third test (in the knowledge of the results of the first post-intervention testing), was conducted on average 128 days from the start. The standardised swab sites were divided into basic ‘hygiene’ areas (floors, tables, work surfaces, kennels, patient kitchen areas) and frequent touch ‘fomites’ (potential fomite) areas (door handles, keyboards, taps, phones, anaesthetic, laboratory analyser touch screens, staff kettles and X-ray controls). All swabs, at all sites, were collected by the author personally, in order to minimise any variability in site selection, collection or test methodology and hence result. Veterinary Practice Hygiene, how well are we doing, could we do better, how easy would it be? Author: Forbes NA. Homer Forbes International, UK. Neil.forbes2011@yahoo.co.uk Keywords: Hygiene measurement, AMR, Infection quality control. Biofilm, airborne contamination, Adenosine triphosophate (ATP) >>>22
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