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.