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Does 90C moist heat incubator cleaning cycle really kill fungus? - (Feb/09/2011 )

Hi! We use Heracell incubators, with fans, with the 90C "ContraCon" moist heat decontamination cycle, which are cleaned about once a month. As I mentioned in a previous post, we have been having pretty bad Aspergillus contamination for a long time now. It is growing in through the neck of the small flasks only, and starts showing up a couple of weeks after the incubator is cleaned.
I think it's coming from the incubator fans, because some of the fan housings have obvious blotches of stuff growing on them, and because they are impossible to manually clean if you aren't allowed to physically disconnect and remove them from the incubator (which I am not). Also, the majority of infections are occurring in flasks on the top shelf of the incubator, closest to the fan.

So far we have assumed that the ContraCon cycle kills everything in the incubator as advertised. My coworkers did some testing with agar plates and supposedly the air in the room is clean. So I am starting to suspect that the cleaning just knocks the fungus back, but it still survives in the fan housing.

My question: Has anybody had a problem with 90C moist heat, or other "decontamination" cycles not killing fungus or other contaminants? Thanks for any info.

-Uncia-

I don't think those cycles will kill fungal spores at all, you would need autoclave sort of temperatures and pressures to do that.

-bob1-

I agree with bob.

The idea that it helps.. its stupid.. I mean: why do you think we use an autoclave at 121C?

I can understand it helps a bit and that its cleaner that other incubators.. but to be really sure you need to be able to clean everything.
And you state you see something on the fans... biofilm..... if there is a biofilm forming.. then forget the moisture heat sterilizing thing...

You need to clean the incubator completely, open the fans or whatever it is.. and really clean it.

-pito-

Dear Uncia,

I agree entirely with Bob1 as usual...it will not kill fungal spores. Only autoclaving at 121oC, 1 Bar pressure for 20 minutes will do the job.
We no longer have fan assisted CO2 Incubators in our 2 Institutes due to the fact that they (the fans) are impossible to clean and then spread spores around the incubator very effectively indeed.

In my experience the cause of the contamination in the first place is researchers NOT wiping their flasks, dishes, multiwell plates etc, with 70 % IMS.....wiping removes any media from the TC plastic, thus making it difficult for fungal spores to take hold inside the incubator.

Kindest regards.

Uncle Rhombus.

-rhombus-

Thank you very much for the replies. I'll work on trying to get the fans cleaned or replaced.

-Uncia-