Monday 26 October 2015

Harriet the Hitch-hiker

For those interested in the initial story, scroll down to yellow text.

January 28th, 2016: The case of ‘Harriet the Hitch-hiker has been solved!  The culprit in this case was a common house dust mite, most likely Dermatophagoides farina.  

I spoke with a former colleague the other day who informed me that months after I left, there seemed to be a ‘bug’ infestation in the mycology lab.  A few parafilm-sealed plates left at room temperature appeared to show surface movement.  When placed under a plate microscope, tiny creatures could be seen chomping away at the fungal growth.  As my colleague put it “it looked just like tiny buffalo eating grass on the high plains!”  

So where did they come from?  Well, they are considered ‘common’ dust mites and so they may have blown in from the hospital environment.   Hospital beds are full of patients, shedding skin and while proper laundering of bedding and other fomites should destroy these critters, the contents  and mites may be shaken off in the process.  They may have been brought into the lab by the cleaning staff or by laboratory staff such as myself.  They may have come from specimens sent from other labs.  Somehow I was lucky enough to find the very first one most likely caught on the adhesive tape roll that I used to make a mount of the proficiency testing sample.

Well, the completed isolates were quickly discarded.  New specimens were temporarily sent to the Provincial Reference Laboratory for workup and the Mycology laboratory was scrubbed down with disinfectant from top to bottom.  The problem has been solved

It was news to me that mites eat fungi but just Google ‘fungi eating mites’ and you’ll get a number of references and even a YouTube video for those who want to see these mites in action.

Just a few Notes:

Mites are eight-legged, sightless arthropods that live on skin scales and other debris.  The most common house dust mites are:

Dermatophagoides pteronyssinus –known as the European dust mite

Dermatophagoides farina –known as the American dust mite

The common names may be misleading as neither species is restricted to the location in their name.

Euroglyphus maynei - is a third species of dust mite, however, because of the high water content of this organism, it prefers more humid environments to replenish itself.

Once source[i] suggests that fungi are an essential component of the dust mite’s life cycle.  Though not fully understood, it may be that the fungi utilize some of the same nutrients or assist in breaking them down so they may be consumed by the dust mites.  This sounds more like a symbiotic relationship rather than the mites consuming the fungi (fungivore).

The Story of 'Harriet the Hitch-Hiker

So the laboratory proficiency mycology specimens arrive in the lab and I eagerly have a first look at the direct, teased out, samples.  One specimen is labeled as having been taken from the scalp so I suspect the sample may possibly contain a dermatophyte.  Carefully scanning at low power, I search for any tell-tale clues which may provide a ‘head-start’ (no pun intended). Then, I see something unexpected.  Hey! What’s this?  What are you doing here?  Where did you come from?  That specimen from the scalp has brought along a hitch-hiker.  So who are you anyways?  Follicle Fred? Afro Al? Blow-Dried Billy-Bob?  Hmmm, Hairy Harrison? (Hairy Harry to be less formal).....but wait….what do we have here?  Eggs!  That’s not Harry the hitch-hiker….it’s Harriet the hitch-hiker!           

I suppose it was an unintended addition, but our mould sample from the scalp, also contained a tick(?) of some sort.  The specimen donor has more problems than just a possible dermatophyte!             

‘Googling’ ticks brought up the ‘mug shots’ of a number of possible suspects, however, I’ll leave it up to some entomologist out there to positively identify my freeloader and replace the alias with a proper name.

Below are Hitch-hiking Harriet’s mug shots to add to the unsavory lot of ticks, lice and louses imprisoned in cyberspace.  Sorry, she wouldn’t turn for me to get a profile photo.  No smile either!  One tough character!

Lactophenol Cotton Blue is the background stain as I was looking for moulds in this preparation.

Harriet, my unknown scalp tick which hitch-hiked along on a scalp mycology specimen.
(Didn't keep detailed notes on this one.  X100, I believe -Nikon)

Harriet again.  Female for sure -check out the 5 oval eggs in her abdomen
(?250X, Nikon)

Same 'Harriet' but image reversed due to the difference in the optics between the Nikon and the DMD-108 Digital Micro-imaging Device.
(100X, DMD-108)

And the last mug-shot at a higher magnification.
(?100+10X, DMD-108)
 Links below redirect to the identical post within this blog.

While I like using both photographic devices (Nikon Coolpix microscope mounted camera) and the Leica DMD-108 Digital Micro-imaging Device, I feel that each platform has an advantage in different situations.  I like to try both methods and then chose which gave the best representation of the subject I was attempting to document.  Often it is in the eye of the viewer.

What?  you mean you don't give a familiar name to your organisms?

Fun With Microbiology - as the title of the blog proclaims.

*   *   *