Tuesday, July 11, 2017

Case of the Week 452

This week's case was generously donated by Dr. Richard Bradbury. The following biphasic population of organisms was seen after corneal scrapings were inoculated onto a non-nutrient agar overlain with Escherichia coli and incubated for several days.

These objects measure approximately 25 micrometers in diameter.


These objects measured up to 45 micrometers in greatest dimension:


Identification?

9 comments:

M. Prochazka said...
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M. Prochazka said...

Acanthamoeba sp. The smaller structures are cysts and the larger ones are trophozoites displaying spikey-looking pseudopods.

Dario Campese said...

I think amoeba

Anonymous said...

Acanthamoeba sp. I totally agree with M. Prochazka.

Anonymous said...

Great case, the pictures are just textbook and educational quality. Acanthamoeba. The spherical shape with polygonal inside structures are the cysts. These can be observed with a variety of stains including Calcofluor, or even gram stain. The thorny structures are the trophozoites with their acanthopodia. The trophozoite of other amoebas such as E. coli or histolytica/dispar have rounded ends pseudopods.

Florida Fan

Sugar Magnolia said...

I concur. Acanthamoeba sp. in some outstanding pictures! Very nice.

Anonymous said...

Cool case. I predict is a teenager-30s female not boiling or changing contact cases.

So what is best practice handling these patients... remembering the differential is pretty broad, the specimens tiny, and the eye far way from a lab and further away from an E coli lawn. [We have 1 gung-ho "cornealogist" who holds her patients until we send her plates she directly innoculates but that isn't very practical generally.]

Richard Garcia-Kennedy

Anonymous said...

Ooops -- I didn't mean to ask Bobbi to write my lab manual; just if global there are some clever workarounds, etc.

Richard Garcia-Kennedy

Christen Rune Stensvold said...

We use real-time PCR for detection of Acanthamoeba in clinical samples. We are currently experimenting with an exhaustive 16S+18S microbiome profiling of corneal scrapings, since infectious keratitis can be caused by a plethora of organisms (and viruses too, of course).