human pathogens in agar plates

[malook]

Does anyone know the DET's current policy on incubating agar plates which may grow human pathogens ie. the students coughing, spitting etc on plates. I am under the impression that it is not good practice but my HT wishes to do this with Biology class.She feels sealing all around with sticky tape solves the problem, but this leads to the growth of nasty anerobes.

[Anastasia]

I don't think it's a good idea, we certainly don't do it at my school. We stick to skin and surface swabs (but not from the toilet blocks) and get good enough results from these. You are also right that sealing all the way round is not good either, just tape in three spots.

[Krysia Lee]

Absolute no no here. What do you do if one of the agar plates lids cracks etc ? I do believe that isn"t allowed anymore.

[RosalieM]

It's in the CSIS not to do it. Sorry I don't have the folder with me but look it up under something along the lines of microbiological practices. You will find it. If you have no luck get back on here and let me know and I will try to find it for you. It is in the same place where it says you can't unseal and re-plate any growths.

[malook]

Couldn't find it in CSIS can you give me the page/ reference. thanks Rosalie

[RosalieM]

It is page 57 of the second folder (section 3.2.6). It doesn't actually specify coughs and sneezes but it does say no blood or blood products or human tissue. Surprisingly, it also says saliva is OK (as long as noone else touches it) but I'm pretty sure that's no longer the case! It goes on for a couple of pages and covers re-plating etc as well. Sorry I don't know if this will be as much support to you as I first thought. If you can't talk them out of it, make sure you use parafilm instead of sticky tape. You can seal it all the way around and it allows gas exchange limiting the chances of the anaerobic growth.

If you use RiskAssess there is a link there to "Issues relating to culturing of microorganisms" which has as a safety measure "Do not collect microorganisms from toilets, from human body fluids (including from sneezes or coughs) or skin (other than hands and fingers), to reduce the likelihood of culturing pathogens."

Sorry I couldn't be more helpful. Surely in this day and age where everyone is so germophobic it would just seem ridiculous to even try to grow more!!

[RosalieM]

Oh! As an afterthought - I am in a private school, so I don't have access to any of the 'updates' so perhaps if you have access to the CSIS online you could look up the section number and see if there are changes there. My folder is from 1999 I think (that's the date on the CD that came with it). Perhaps there will be something to help your cause there

[RosalieM]

Also, (Sorry, I should have thought for longer before pressing submit the first time!) If you can't talk them out of it, make sure you set your incubator for only about 25deg and don't keep the plates any longer than 7 days. Lay down these rules BEFORE they start and say "this is my work space and I do not feel comfortable having these pathogens potentially floating around and as you insist on performing the experiment, I will insist on safety control measures that will minimise potential contamination to myself" or something along those lines. Say you will be destroying the plates exactly one week later so they know in advance they have to look at them quickly which will mean less growth as well.

[lada]

Has anybody using pre-packed disks with agar (or similar) already on it? Made by 3M?
The top film is peeled back and disc is inoculated and re-sealed. Our bio teacher wants me to look into it.
Lada

[Loopy]

Hi Lada,
I think the discussion of those type of swabs have occurred elsewhere in Chemtalk. I have used the type you are talking about, and they are great but a little bit pricey. Some one here said they actually poured agar onto the swab, but in industry you peel back the cover plastic, and pour sterile water (a few drops) onto the disc and then press the card onto whatever you wanted to check for germs, replace the plastic cover sheet and then incubate. Fairly simple, and then we just threw the card away when finished (whether we were just being lax in the late 90'S I'm not sure...). Hope this helps...

[lada]

Love the disposal technique. Teacher seems to be OK with price, so I hope we will try them. I am over making agar, as teachers do not synchronise their lessons and they drag the whole procedure for a few weeks. This way, I can always have the cards on hand.
How little I need to make me happy.
Lada

[malook]

Thanks all, especially Rosalie M. I don't incubate anything from that prac at 37 degrees as a safety measure already.Cheers

[LabMad]

CSIS online

(b) Use of human tissue in experiments

Experiments using fresh human blood or fresh human tissue, e.g. cheek cell smears, should not be undertaken. Teachers are to use only commercially prepared slide preparations to study the cellular components of blood and are not to undertake practical work to determine students' blood groups (e.g. A, B and O).

Refer to Board of Studies memorandum BOS 46/95: Use of fresh blood in experiments, April 1995. Refer to Section 3.2.6.1.

.2.6 Safe use of biological materials/organisms/tissues

3.2.6.1 Human blood, tissue and fluid

Human blood, blood products (other than commercially prepared microscope slides of blood) and human tissue, e.g. cheek cell smears and urine, must not be used in science practical work. There is a risk, although statistically very slight, of contracting a virus such as HIV, Hepatitis B or C from incorrectly or carelessly performed experiments involving blood or tissue.

Since it is not possible to guarantee the complete safety of students when undertaking experiments using human blood or blood products, teachers are to use only commercially prepared microscope slides to study the cellular components of blood and not to undertake practical work to determine blood groups.

There is little hazard from saliva, and only if students, teachers or SASS come into direct contact with saliva other than their own. If a student uses his or her saliva, he or she should be the only person to fill, handle, empty and wash out the glassware before placing it in an undiluted bleach (sodium hypochlorite) solution. Take care not to splash bleach solutions on clothing. SASS must be warned that saliva has been used and should wear gloves when carrying out the final clean-up of the glassware.

Mouth pipetting is not allowed - always use a pipette filler.


3.2.6.2 Microbiology

Very large numbers of potentially harmful organisms may grow in experiments involving the culture of micro-organisms on nutrient agar in Petri dishes. The Petri dish can become a potent source of infection after incubation.

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Approved activities

The subculturing of bacteria from wild cultures must not be performed in DET schools.

However, commercially obtained pure strains of non pathogenic bacteria can be subcultured from one plate to another, provided the appropriate safeguards are followed.

Microorganisms are classified into risk groups in Safety in Laboratories: Microbiology, AS2243 Part 3, Standards Australia (1995). Only use organisms from Risk Group 1, which are classified as "unlikely to cause human, plant or animal disease" and are commonly found in the environment. Some of these are found in commercially available biotechnology kits or from commercial biological supply companies. Examples include:

Bacteria

Bacillus subtilis
Escherichia coli
Rhodospirillum rubrum
Sarcina lutea (Micrococcus luteus)
Serratia marescens
Staphylococcus albus (Staphylococcus epidermis)
Fungi/Yeast

Mucor
Penicillium
Aspergillus
Saccharomyas
Lactobacillus acidophilus (from yoghurt) or Lactobacillus casei (from Yakult) are safe strains that can be easily obtained.

If there is any doubt about the purity of the bacterial sample, it should not be used.

Subculturing of blue/green mould from oranges or lemons to verify Koch's postulates can be carried out by senior students provided aseptic techniques are followed under the guidance and supervision of a science teacher experienced in microbiology techniques.

Ensure cultures are incubated at temperatures below 30oC.
Dispose of or clean all Petri dishes after use as described for bacterial cultures below.
Dispose of mouldy fruit in sealed bags to garbage.

[macca]

Just had a teacher ask for a practical for Year 8. The prac. is from one of the brand new NSW Australian Curriculum text books.

One of the instructions are as follows "Use a cotton bud to swipe a part of your body (such as the inside of your nose, your teeth, inside your ear or you scalp) then swipe the cotton bud on the surface of the agar plate.

Am I missing something!!!!!!!!!!!!!! as you know text books are always correct "but it says we can do it", another teacher has said to me. I'm trying to be sarcastic Nose teeth ears that's not bodily fluids really.

Or am I wrong!!!!!!!

[smiley]

You are not wrong. NO human pathogens. No no no.

What's the purpose of the prac anyway? Looking at "germs" or something more specific?

[macca]

Thanks Smiley I didn't think I was going nuts I'm so used to saying no no no.

The Title of the Prac., is "Where are those germs"

[smiley]

The Title of the Prac., is "Where are those germs"

And the answer is: Not in my lab!

[macca]

ha ha I wish; but with 800 snot juggling gremlins coming through each day I'd say heaps of germs. Darling cherubs

[rae]

Macca ,
I've just looked and this is the text book we use too. I don't understand how text book can be written that potentially encourage bad practice and potentially put us and the students and teachers at risk. Where is there risk assessment?
There are other pracs in these books that I look at and just think where the hell do they get them from and have the authors ever actually performed these pracs because they are crap!!

[MariaC]

I agree Macca, there's one that gets the students to light a bunsen burner and then tilt it to burn a substance (flame test from memory)! I instantly banned it, who gets students to handle a lit bunsen burner???? when much safer and proven methods are available.
MariaC