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How to work sterile in a LAF room

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#1 josse



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Posted 15 April 2009 - 09:11 AM

I have seen some strange things in a microbiology lab that I visited today with school and wanted to know what you all think about it.

First there was a person that washed his hands with ethanol outside the laf, after doing this he took some things from a table outside the laf. Why bother washing your hands if you do it outside the laf and afterwards take some stuff outside and then start working under the laf. But that wasn't all. He dropped his pipettetips outside the laf in some plastic bag, so he moved his hands outside the whole time. Is this ok?
According to me his hands were not sterile since he moved them outside every time he dropped his pipettetips and he touched his stuff (small tubes he had to fill, aseptically, with his suspensions and primers) under the laf. Or am I wrong here?

Another one opened a box of pipettetips, said to herself: oh not the right ones and closed the box again, this box was still standing outside on some table. So goodbye sterile tips... she did leave the box on the table, so others would still think they were sterile. Well thats how I always was told, or am I so wrong here?

Also saw the following: someone opened a box of pipettetips under the laf, this was ok, but he placed the lid (the one to close the box) on the laf table (still ok) but then he placed the box on this lid (the inside of the lid). When finishing he placed the lid back on the box ===> byebye sterile tips, because that box was standing on a table outside the laf, so the outside of that box was not sterile, so if you put the (outside of) box on the lid (inside of the lid,when closing box) the tips will be contaminated.
Or am I again wrong here and is it ok to do this?

Another one was working under the laf, but moved his arms the whole time over an open box with pipettetips, the ones he used, good bye sterile pipettetips I would think?

I also noticed that they did not clean the whole laf before starting. They just cleaned a little piece of the laf with ethanol, not the complete surface nor the side of the laf.

Another funny thing: they took samples (small plastic bars) and placed them in a not closed jar, moved those to the laf and started working with those under the laf... whats the point to take samples and to process them under the laf when you simply walk around with those samples in a not closed jar from the place where you take the samples (basement) to the place (second floor) where you process them?
The funny thing was that they wanted to check how many bacteria where on those plastic bars. Bars were kept in water, representing a water flow of a diary farm. I understand you cant take those bars aseptically out the water, but you could do some effort and put them as soon as possible in a closed container to minimize contamination. They took about 20 bars or so, so you can imagine if those bars stand there the whole time, waiting till you move them upstairs to process them you would get contamination or not?

I found this very strange to see, or am I a hair-splitter here and is it ok to work like that?

Edited by josse, 15 April 2009 - 09:14 AM.

#2 little mouse

little mouse

    Missele, the little mouse

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Posted 16 April 2009 - 12:59 AM

ha ha you are a hair-splitter, but I will hire you if once I'm looking for someone.

When we work in a laf as we work usually, we are not working sterile. It's impossible alone. You must be 2. one wear sterile labcoat, and sterile gloves. He has to put them inside the hood, but cannot bring the gloves in their bag inside the hood as the outside of the bag is not sterile. So, someone else has to bring the bag, open partially it and present it to the guy that will work under the hood, close to the hood. and this is the same for everything else. every thing has to be in 2 bags, the first opened outside the hood by an colleague, but close to the hood, then the second bag (sterilee) is quickly transfered inside the hood by the "sterile" guy that is working inside the hood. A little complicated, isnt it?
Usually, we work as much clean as possible. for most of the applications it's enough.

About the open box, I don't know how it works in all labs.
I never consider that a opened box standing outside the hood is sterile. It would be more polite not to let non sterile tips in a cell culture, in any way but you have to be careful, and always use box you opened yourself.

you should not move over an open box

you should clean the hood with detergent, and then with alcool after use. jsut to be safe, you can clean again with alcool before to start. The whole hood (the side, under the working place...) should be cleaned and desinfected once a month)

About the bars, I don't understand exactly what they did.

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