I have a question about acceptance criteria for microbiological swabs in cleaning validation in manufacturing of medical devices.

It is non-sterile device (coated tubes) manufacturing. The equipment for validation is cleaned only with purified water and it is made from steel (and tubes are silicon). Manufacturing area is not a clean area or controlled area (no limits for MB bioburden, no data from MB monitoring). There is not a MB limit for finished product bioburden(I am not able to calculate any limit for MB bioburden in one batch).

And there is no possibility to perform validation of MB swab method (to evaluate a recovery of MB swab).
I think that limit 100 CFU/cm2 is OK, but I don´t know any regulation, which estimate this limit and I need it, because every body asks-where did you get this limit?

Please, do you know any regulation, which prescribes the limit for MB acceptance criteria for cleaning validation in this cases?

Do you think my limit is OK?

All help welcome.

Best Regards