sorry cfu/swab so cfu/100cm2 actually.
Having a higher than normal count on a surface that was sanitized is concerning. As a reference, if I expect an area to have under 100cfu/g but comes back over 25000, and after we clean again it comes back at 2000+ I am concerned. I wonder what the bacteria are that are surviving and I make the assumption that it is something that is able to resist cleaning agents, mainly spores from spore forming bacteria.
Hi ebb,
Thks for numbers.
i deduce you target a max. level of 100cfu /100cm2, ie 1cfu / cm2
IMEX this is an attainable but quite demanding expectation (see below). It's achievance surely relates to a variety of specific variables (see below).
From a survey/compilation of published global data posted elsewhere in this forum (prob.mainly wet scenarios) i concluded -
For Aerobic Plate Count (APC) - the majority of data suggests that, for routine cleaning/sanitising, surfaces typically have maximum APC counts in the range 10-100cfu/cm2
(there were some expectations both above and below this range, ideally should perhaps consider the "maximum" as an average of a series for a given "area").
http://www.ifsqn.com...ces/#entry60958
IMO the nature of the variability of initial surface condition / cleaning/sanitizing procedure / swabbing prodecure / analytical reproducibility of bacterial data (!!) almost guarantees large variations/confidence ranges in the APC data. This is further added/reflected by the considerably varying opinions as to desirable levels in the literature. Published acceptance levels typically allow for wide variations.
IMO a level of 25000 (ie 250cfu/cm2) would be a little high if consistently occurring but if a random result needs to be confirmed by, for example, repeating in duplicate/triplicate to assess the average/range. Trending is equally important IMO, eg where is the (hopefully satisfactory) baseline ?
From yr comment /10x reduction on "further" cleaning i would initially suspect that yr cleaning step is varying in efficiency for some reason (or the surface, or both). Poor cleaning will (obviously) increase the APC result for a given initial level of contamination of viable bacteria but will also likely interfere with the sanitizing step so further lifting the APC result. Comes back to setting the baseline, ie can it comply with max 1cfu/cm2 ?
Just some thoughts. My area of experience is mainly in wet processing where the problems are likely rather different.
Regarding types of bacteria, it is always possible to request lab data on some usual suspects, desirable in fact since APC is not considered a safety-related variable.