Cleaning Management

by Prof Chris Griffith

In the last article on the rise and rise of cross contamination the importance of cleaning was highlighted.  Cleaning, in conjunction with hand hygiene are the main weapons in preventing cross contamination.  Food premises need to be designed and constructed appropriately (see Section 7.2 of SANS 10049:2011).  You cannot clean a surface that cannot be cleaned!  Section 7.4.5 contains useful advice on cleaning itself.  Cleaning is defined as the removal of soil (matter out of place) including food and other residues.  Disinfection is defined as the destruction of microorganisms and can be achieved by physical (e.g. heat) or chemical methods.  However, surfaces must be clean before chemical disinfectants will work.

In order to avoid contamination food contact and other surfaces will need to be cleaned and possibly disinfected to avoid the spread of pathogenic (disease causing) microorganisms.  The new SANS document also provides some advice on how cleaning should be managed.  This starts with having documented cleaning protocols.  These are usually contained within cleaning schedules and should specify how, when, with what and by whom items are to be cleaned.  Ideally the effectiveness of such protocols  should be validated (i.e. proven to be effective) before being used.  In other circumstances you would not buy an item before finding out if it works!  Cleaning should also be monitored although SANS 10049:2011 refers only to microbiological testing and the related SANS 5763:2006 edition 2.  This standard  is relatively outdated and does not even cover aspects of surface testing found in ISO 18593 which itself is not a very good standard.  In reality microbiological testing is not a measure of cleanliness but of disinfection.  Cleanliness can be assessed visually although in isolation this can be misleading, visually clean surfaces can be coated in soil and/or microorganisms.  Nevertheless there is no point in any further testing of surfaces  which are visually dirty – they are not clean and need to be re-cleaned.  Much more sensitive tests for cleanliness are now available including tests for residual protein or ATP with the latter most widely used.  These are much more accurate  and provide a better of indication of  cleaning efficacy and surface cleanliness.  An additional advantage of these methods is their speed with in some cases results available within 12 to 15 seconds.  Surfaces failing the cleanliness test can prolong microbial survival, support pathogen growth and contribute to biofilm formation. These can then  be tested for surface disinfection ie microbial contamination  using  a range of methods  including swabs.  However, for relatively flat surfaces contact plates, dip slides or petrifilm provide superior precision and accuracy when compared to swabs.

There is no single ideal test method but collectively visual, ATP/protein and microbiological testing provide a valuable integrated test approach to assessing the efficacy of  cleaning  and disinfection.  The results of monitoring cleaning/disinfection should  then be subjected to trend analysis.  Failure to do this misses out on the real value of surface testing and could result in another Maple Leaf type Listeria monocytogenes outbreak.  This outbreak in Canada killed 22 people and cost over $20 Million and the failure to monitor cleaning trends was a major contributory factor

Cleaning protocols should also be verified – long term proof of their use and effectiveness. Cleaning audits as well as reviewing the trend analysis  results are both useful activities in verification .

Science is increasingly showing us how microorganisms possess mechanisms to resist our best attempts to remove them from food premises.  One of the best at resisting cleaning and disinfection is Listeria monocytogenes (the topic of a later article).  Post processing contamination, linked to poor cleaning, is the most likely reason for its presence in ready-to-eat foods.  The previous  article contained a case study on Listeria showing its contamination of multiple surfaces within a food plant and its presence in the factory  for over 9 months, in spite of cleaning and disinfection.  Evaluating and improving the cleaning and disinfection regimens  resolved the issue.

In summary cleaning and disinfection are two different but important related  activities in preventing the rise and rise of cross contamination.  To be effective cleaning protocols need to be documented, validated, monitored and verified.  These processes require an effective testing strategy for cleaning  and should not just be based on microbiological methods.


Answer to the question from the last article:
Episodes of the X-files often involve unseen life-forms and strange happenings. In a sense cross contamination also involves these with unseen microorganisms spreading and moving rapidly around food premises in an apparently mysterious way with the potential to remain hidden for years.

This week's Question:
How clean is clean?



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