Get Moldy

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         Finding mold growing in your agar plates is not uncommon. They could be legitimate organisms growing from patient samples. Sometimes, they are contaminants from handling or even the manufacturing process. The most important thing is to sub the fungal growth to another media to carry on testing.

         In my case, it was necessary to remove all agar plates of the same patient, from the same set, from the automation. The worst thing is to have spores get loose and contaminating an entire incubator. Trying to decontaminate after the fact is a huge, unfun, hassle.

         When handling actual mold growth, it's imperative to perform everything under the hood. For an extra layer of security, the room which we handle the likes of fungus has negative pressure.

         In short, I cut out a piece of the agar with mold (I prefer using the 10ul loops) and transfer it onto a potato flake (PF) agar. The PF allows for better morphological observations of fungal growth. I would then seal all the plates with parafilm until further testing.

         I then transport the original plates to an offline (not part of automation) incubator. This is for bookkeeping as the original order is not an exclusive fungal culture. The subbed PF would go in a dedicated incubator in the negative pressure BS3 room.

         When grown, another lab personnel would stain them with lactophenol cotton blue. Through a combination of light microscopy and morphology, we would attempt identification. We may also consult pathologists as necessary and they may order other tests as they deem fit.

         In the above example, the sample was from a butt abscess. Yes, fungus can grow anywhere. From the looks of it, it might be some sort of Aspergillus. As for seriousness, I wouldn't know. I did not have enough context to know other than the fact this was not a surgical sample.

         Mycology feels like one of the lost art of microbiology sometimes. Part of this is because only a handful of people in the department have had the specialized training for it.

Posted with STEMGeeks



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24 comments
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Fungi can be really difficult atimes.

This was beautiful and your technique was well explained.

I liked it, it reminded me of my undergraduate days

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Yeah, they always require extra work.

Appreciate the tip!

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Yeah, they always require extra work

I discovered.. And they can be difficult to treat

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I did not have enough context to know other than the fact this was not a surgical sample.

I'm going to share my prejudice on a mental image of a patient that's immunocompromised and having that butt abscess gives me a string of differentials that lean on them having an adventurous lifestyle. Well from experience these cases I see here tend to go towards that direction unless they are getting immunocompromised for other reasons like chemo, inherited immunodeficiencies or extremes of age.

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Well, if you want more clarification, it was abscess of the buttocks.

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The lost art of microbiology... I love it :)

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I really don't know many people who do it.

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I meant, I loved the expression. I do also not know any expert in mycology.

To chitchat a bit, the last time I personally ended up with mold was in a hotel close to Reims. Believe me, I was quite unhappy, even if the hotel did actually everything they could to get those molds. I mean, building a bathroom without any ventilation system. What a crazy idea...

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Potato flake sounds like some sort of special snowflake ( the human kind not the falling from the sky kind ) :P

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(Edited)

I have not worked with PF agar but I did use Malt Extract Agar to grow mushroom mycelium from a mushroom cutting. From there you can place it in a growing medium like washed wild bird seed or brown rice flour. Its pretty amazing how quickly it grows and yeah I would get contamination sometimes.. Usually trichoderma as my clean air box consisted of a plastic storage container with glove cut outs. I would spray my gloves with lysol and clean the inside and out after use but after about 15 or so uses it would consistantly grow trichoderma so I had to toss it.

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That’s pretty cool.

The PF is to grow mold, so I’d imagine it’s less useful for growing mushrooms.

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