Sunday, 7 June 2020

Cleaning validation Q&A


Recently Pharmig ran a session on cleaning validation. Here are some of the questions posed, together with the answers.


This is obviously not easy. If the surface area is smaller, then the count is still assessed as if it was 25cm2 (to indicate what a ‘norm’ is and to allow a comparison to be made). With other areas, all you can do is gain an approximate assessment in terms of the number and length of strokes. It is generally accepted that where a template cannot be used, the swabbing is approximate.

How can a swab template be used for the irregular surfaces? If not, what justification may be used?

A swab template cannot be used on an irregular surface, all you can do is gain an approximate assessment in terms of the number and length of strokes. It is generally accepted that where a template cannot be used, the swabbing is approximate.

Where you can, it is best to use a contact plate – it gives a better recovery and if there are cleaning residues present, the agar can contain an appropriate neutralisers.

Are there any regulations or guidelines for swabbing in this manner?

Not for microbiological swabbing. There are a number of good guidance texts, although these are not ‘standards’. The microbiological aspects are invariably overlooked, which was the reason for putting the webinar together.


How can training be provided for personnel to encompass this irregular swabbing?

Pharmig have run too training courses run by Gordon Farquharson in relation to this.

The best way is to use old items of equipment and allow personnel to practice on the lab bench, assessing their technique e.g. number of swab strokes, twisting the swab head etc.

Also when swabbing a surface do companies use cut out templates to get an accurate surface area? Or do companies just go on samplers judgement of surface area- between different samplers this could introduce a lot of variability?

Some companies use templates, which are sterilised. These will only work on relatively flat, regular shaped surfaces.

Others use judgement, and this has to be applied to irregular shaped surfaces. This can be supported by training.


As cannot contaminate equipment with organisms like can with chemicals. What does he think to the suggestion of supplementing cleaning validation study with lab based studies on samples of surfaces representative of the equipment? E.g. samples of SS 316L in lab – could contaminate with organism(s) representative of those found in facility and demonstrate effectiveness of cleaning regime/agents etc. is possible.  Overkill & unnecessary or good to do if have the time & resource?

This is useful if there is sufficient resource. The method outlined is similar to disinfectant efficacy testing in terms of phase 2 surface evaluation. However, it is not (as yet) a regulatory requirement. The standard approach is to evaluate ‘cleanliness’ through direct (swabbing) and indirect (rinse) samples.


The reference to facility isolates is interesting, although these are difficult to standardise.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

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