Incubator usage (Contaminated vs Non contaminated) - (Jan/23/2014 )

Hello,

I have a question regarding incubators. Where I work, we segregate our so called contaminated work (intentionaly contaminated media/agar plates) and non contaminated work (product analysis wich are usualy exempt of bacteria).

Is there any pertinance in doing so? If not...are there any controls (periodic air sampling) that are needed to be done in order to eliminate the possible contamination factor (or to prove that it is not the incubator who contaminated my plate and gave me a false result) IF we put all our work (contaminated and non contaminated) in a single incubator?

Thank you in advance!

I am not advice the researcher to incubate both contaminated and non-contaminated plates in one incubator. However, if you do so, the chances for  contamination is low since you invert the plate while incubation. Btw, you can prepare a control plate (the empty agar without bacteria), incubate overnight, to determine whether the incubator or your culture itself is being contaminated. 

If you are worrying the incubator is the main cause of contamination, you can clean the interior site of incubator by using 70% alcohol. 

Hope it help. 

By "contaminated" I assume you mean inoculated with a material you expect should include viable microorganisms - bioburden.  Suggest this is not defensible and adds bias to your testing. Any decent auditor would bust you on it.

If indeed the "contaminated" incubator increases risk of unwarranted bacterial isolation - you'll be likely to find growth by lab error in what you think should have bioburden. Observations will be biased by your preconceived notion of microbial presence.   In the "non-contaminated" incubator work - the preconception of lack of bioburden can compel unintentional (or even intentional with some folks) failure to observe growth.

I'm with Enthusiast.  If there's an issue with an incubator - fix it..

Thank  you both for your input. Yes Phil, by contaminated I mean I intentionally inoculated with a bioburden.

So if I understand it correctly, it is best to separate my 'contaminated' work from my so called non intentionally contaminated work right?

Thank you again

Oh and Phil, nice dog you have there!

I'd incubate these together rather than in seperate incubators.  Are the intentionally inoculate growth promotion plates?

and thank,s aenhim - best dog i ever had!!

Well, everything (plates or liquid media bottles) that are intentionnaly contaminated (growth promotion or preservative efficiency tests) are incubated in a specified incubator and our so called not intentionnaly contaminated work (product testing/media sterility) is placed in another incubator.

We work with both bacteria and yeast/mold pathogens, I agree that bacteria cant jump from plate to plate...but spores could...

I cant find anything (USP/EP) that requests the segregation of contaminated vs non contaminated plates/liquid bottles, so I belive that we are over protecting ourselves.

What do you mean when you say: ``Suggest this is not defensible and adds bias to your testing. Any decent auditor would bust you on it.`` ?

Thanks again

Just that expectations drive different treatment of plates in a manner difficult to justify.