Decontamination
l Outbreak control by disinfecting cleaning within bundles.
The criteria for the selection of disinfectants are determined by the requirements for: effectiveness, the efficacy spectrum, the compatibility for humans and the environment, as well as the risk potential for the development of tolerance and resistance. The recommendations also provide detailed guidelines on cleaning and disinfection measures – including structural and equipment requirements; the pathogen characteristics for acquisition (i.e. tenacity, infectious dose and biofilm formation); the toxicological and ecotoxicological characteristics of microbicidal agents; the basis for their selection; and the methods for the evaluation of the resulting quality of the cleaning/disinfection of the surfaces. Martin explained:
l Hands are the main source of exogenous transmission (accounting for 5-20% in Europe).
l Surfaces can also be a relevant source of contamination.
l Hand hygiene and indication-based surface hygiene need to be complementary.
l If the necessity of disinfecting surface cleaning/surface disinfection is unclear in any given case, biocide should be applied after weighing the risk of infection against the risk from handling the hazardous substance.
The recommendations also provide a list of disinfectants that have a valid certificate from the Association for Applied Hygiene (VAH, Verbund für Angewandte Hygiene). The certificate is only issued when the product satisfies the efficacy requirements published by the Disinfectants Commission. Martin added that ‘surface cleaning’ is defined as follows: l Cleaning processes are intended to remove impurities (e.g. dust, dirt, organic substances such as blood, secretions, excretions) using water with cleaning enhancing additives (e.g. surfactants).
l This process also removes microorganisms mechanically without actually or intending to kill/inactivate them.
The definition of disinfection, on the other hand, is: ‘a process that reduces the reproductive microorganism count to a level assumed to be harmless in terms of infection hygiene by killing/ inactivation, based on the latest standardised, quantifiable evidence of effect, in accordance with the most up-to-date knowledge, with the objective of converting the condition of an object/area into one that no longer poses a risk of infection’. Cleaning versus disinfection is determined by:
Transmission routes
contaminated surface
indirect transmission
direct transmission (contact, air turbulence)
hands of staff/ other patients/
third parties (visitors) Figure 1. Transmission routes starting from contaminated surfaces
l The probability of microbial contamination. l The potential for shedding pathogens where the differing patient risks result from the colonisation, suspected infection, or infection of the patient.
l The probability of staff or patients being directly contaminated from the surface.
l The requirement for a pathogen-free environment during aseptic activities (e.g. preparation of infusion solutions, enteral nutrition solutions, provision of injection equipment, preparation of medicinal products in the pharmacy/operating theatre.)
l The patient’s susceptibility to infection. l The risk to staff posed by pathogens.
Martin pointed out that there is a growing body of evidence on the association between environmental contamination and the risk of infection. He highlighted a ‘before and after’ study, which investigated the impact of disinfection on the rate of CDI. By switching from a chlorine-based surface disinfectant to cloths containing peracetic acid (PAA), the rate of CDI was reduced from 6/1,000 patients to 2/1,000 patients. Changing from a quaternary ammonium compound (QAC)-soaked cloth to hypochlorite disinfection reduced the rate of CDI by 85%, from 24.3 to 3.6/10,000 patients. In two other ‘before and after’ interventional studies, the incidence of CDI was reduced only at relatively high endemic rates after substituting a QAC for hypochlorite; it then increased again after reverting to a QAC, and was once again reduced upon switching to hypochlorite. He emphasised that disinfection of near- patient surfaces has the potential to prevent nosocomial infections. The five indications for surface disinfection are: 1. Disinfecting surface cleaning of near-patient
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surfaces as part of standard precautions (non-targeted surface disinfection) – in particular, for frequently touched surfaces.
2. Targeted disinfecting surface cleaning or surface disinfection after contamination with potentially pathogen containing material.
3. Surface disinfection before aseptic activities on the work surface.
4. Terminal disinfection. 5. Disinfecting surface cleaning as part of a bundle of measures to control outbreaks.
Martin added that the recommendations include a useful table of cleaning and disinfection measures, based on the risk of infection, which can be used to aid decision-making. For example, for an area that is at ‘increased risk for infection’, such as a neonatal intensive care unit, the area-specific measures should include: disinfecting surface cleaning/surface disinfection for frequently touched or near- patient surfaces; the floors require disinfecting surface cleaning; and rarely touched surfaces require cleaning. However, for areas without increased risk of infection, such as staircases and corridors, the area-specific measures are simply specified as ‘cleaning’. Martin went on to present some
recommendations around resistance and microbicidal active substances. He highlighted that among the disinfectants used for surface disinfection, the development of resistance has so far only been demonstrated for QACs. Therefore, in the event of an MDR-strain outbreak, surface disinfectants based solely on QAC should not be used. He further highlighted the problem of sinks, showers and drains in hospitals as potential reservoirs for pathogens. There are also known issues with antimicrobial substances found in toilet, sink and shower
susceptible or infectious patient
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