The efficacy of a disinfectant can vary greatly depending on the intrinsic qualities of the microorganisms as well as the chemical and physical environment, in which it is being used . Meticulous cleaning prior to disinfection decreases the microbial load and thus prepares the surface for disinfection. The objective of this paper is to highlight the importance of cleaning before disinfecting, which is a critical component of an effective biosecurity program. This will lead to a more informed decision when selecting which chemistry to use under challenging conditions.
Only surfaces that come into direct contact with the antimicrobial for the approved contact time will be disinfected. Hard water scale, organic material and biofilm can all act as a 'shield', which prevents the disinfectant from reaching its target. Cleaners are formulated to remove specific types of soils. Alkaline cleaners are best at removing proteinaceous or organic soils whereas, acidic cleaners are best at dissolving hard water scale. For example: u sing a toilet bowl cleaner (acidic) to remove dried on spaghetti sauce from dishes or a dish soap (alkaline) to remove soap scum and scale from a shower stall are not going to be very effective. Cleaners are also formulated around their functionality. Non-foaming cleaners are designed for applications where high levels of foam are undesirable, such as a tray wash machine. Foaming cleaners provide longer contact times, which help aid in the penetration of soil making them easier to remove. This is particularly relevant for vertical surfaces. Chlorinated cleaners assist in bleaching or whitening the surface. And lastly, neutral pH cleaners are used on sensitive or soft metals that may be susceptible to corrosivity from highly concentrated products.
Biofilm is a layer of microorganisms contained in a multilayer matrix starting with a monolayer and then developing into a microcolony. If the colonies are not separated or removed from the surface they anchor themselves more permanently to the surface and continue to grow. Additional dust, organic material and other pathogens get caught in the sticky matter becoming extremely difficult to remove. High pressure water alone cannot break the surface tension or the biofilm and a formulated detergent is needed to remove the biofilm prior to disinfection. The first and best option to prevent biofilm is keeping the surface clean and dry from the start.
Just because a surface looks clean, it does not mean it is clean of all pathogens. Cleaning is a critical aspect of effective Biosecurity programs. Selecting the right cleaner for the task will help break adherent films associated with scale and mineral deposits from iron and hard water and help reduce costs on labor and water usage. In doing so this will allow the registered disinfectant to work more effectively.